Bovine Flashcards

Question

Nine out of 100 adult cattle are found weak, depressed, and staring into space. On physical exam, they are found to be pale, icteric, and febrile. None of them have hemoglobinuria. The nine cattle all arrived at the ranch approximately one month ago. **What is your most likely diagnosis?** - Leptospirosis - Anthrax - Bacillary hemoglobinuria - Anaplasmosis

Answer 1

Answer: **Anaplasmosis** Explanation The correct answer is Anaplasmosis. The causative agent is Anaplasma marginale. The clinical signs are fairly straight forward, and you need to pick up on a couple key features. The fact that new adults are sick is one feature because cattle are resistant to clinical Anaplasmosis as calves. Also, it should be remembered that hemoglobinuria with Anaplasmosis is never seen because it is all extravascular hemolysis. Since there is no hemoglobinuria, leptospirosis, bacillary hemoglobinuria, and anthrax can be ruled out. Additionally, icterus with anthrax is not seen. *The most likely diagnosis is Anaplasmosis, caused by *Anaplasma marginale*. Key signs include weakness, depression, pallor, icterus, and fever, especially in newly arrived adult cattle. Unlike other conditions, hemoglobinuria is absent due to extravascular hemolysis. This rules out leptospirosis, bacillary hemoglobinuria, and anthrax, where hemoglobinuria and different signs occur.*

Answer 2

Answer: **ELISA for BLV antibodies** Explanation The best answer to this question is ELISA for BLV antibodies. A biopsy is definitive if you can demonstrate antigen with immunohistochemistry, but many diagnostic labs do not have this capability, so this answer option was not included for this question. The ELISA for BLV only reveals that the cow has antibodies to BLV virus, but not that she has clinical lymphoma. However, multiple enlarged lymph nodes and a positive BLV antibody test are strongly suggestive of lymphoma. A negative ELISA test would rule out BLV and associated lymphoma. Aspiration of lymph nodes can lead to false positives, as many inflamed reactive nodes in cattle can have cells that look neoplastic. The AGID for BLV antibodies is less sensitive than ELISA. The WBC and lymphocyte count lacks sensitivity and specificity. *The most definitive test for diagnosing lymphoma in a cow with suspected bovine leukosis virus (BLV) is the ELISA for BLV antibodies. While it indicates BLV exposure, it strongly suggests lymphoma when paired with multiple enlarged lymph nodes. A negative ELISA rules out BLV and associated lymphoma. Other methods, such as lymph node aspiration, can lead to false positives, and AGID is less sensitive than ELISA.* **Bovine Leukosis: Comprehensive Information** Definition • Bovine Leukosis (Bovine Lymphosarcoma): A cancerous disease caused by Bovine Leukemia Virus (BLV), an oncogenic retrovirus. Etiology and Transmission • Causative Agent: Bovine Leukemia Virus (BLV), a C-type oncogenic retrovirus. • Transmission: Primarily horizontal through blood transfer (e.g., contaminated needles, dehorning tools), and rarely vertical (transplacental or via colostrum). Epidemiology • Prevalence: High in US dairy herds (~46.5%) and lower in beef herds (~10.3%). Pathogenesis • Infection Outcomes: • Asymptomatic: Most animals show no signs. • Persistent Lymphocytosis: ~29% develop this benign condition. • Lymphosarcoma: <5% develop cancerous tumors. Clinical Findings • Juvenile Lymphosarcoma: Weight loss, fever, dyspnea, bloat, and posterior paresis. • Thymic Lymphosarcoma: Cervical swelling, dyspnea, bloat, jugular distention, tachycardia. • Cutaneous Lymphosarcoma: Cutaneous plaques, enlarged lymph nodes. Diagnosis • Serology: ELISA and PCR for BLV detection. • Cytology/Histology: Biopsy for diagnosing lymphosarcoma. Treatment and Control • No Treatment: No effective treatment; symptomatic care with corticosteroids. • Control Measures: Testing and culling infected animals, disinfection of equipment, using single-use needles. Prevention • Blood Precautions: Avoiding exposure to blood from infected animals. • Colostrum Management: Using colostrum from seronegative cows. • Farm Practices: Cleaning equipment and facilities, controlling flies. Zoonotic Risk • Human Risk: Potential, but not well-established, zoonotic risk through ingestion of unpasteurized dairy products.

Answer 3

Answer: **Anaplasmosis** Explanation This tick-borne disease has an incubation period of 2 to 4 weeks, and causes these exact signs. Tetracycline is the best treatment. With piroplasmosis or Clostridium novyi type D infection (bacillary hemoglobinuria), one would expect intravascular hemolysis and dark urine.

Answer 4

Answer: **Diazepam** Explanation The correct answer is diazepam. The clinical signs that are described are those of an anaphylactic reaction to the transfusion. Diazepam will not help you in this situation. Epinephrine, antihistamines, dexamethasone, IV fluids and oxygen are all possible treatment options.

Answer 5

Answer: **Babesiosis** Explanation Babesia bigemina and Babesia bovis are red cell parasites of cattle found in the Americas and spread mainly by Boophilus ticks. Other species of Babesia can infect man and other animals and are found on most continents. The disease they cause is characterized by hemolytic anemia, hemoglobinuria (which differentiates it from anaplasmosis), icterus, and death. Bovine babesiosis is also called piroplasmosis, red water, Texas fever, or tick fever. Eradication of Boophilus ticks has been an effective means of control in the United States. The most likely diagnosis is babesiosis, caused by *Babesia bigemina* or *Babesia bovis*, red cell parasites spread by *Boophilus* ticks in the Americas. Babesiosis leads to hemolytic anemia, hemoglobinuria (distinguishing it from anaplasmosis), icterus, and death. Known as piroplasmosis, red water, Texas fever, or tick fever, eradication of *Boophilus* ticks controls the disease. **Babesiosis in Animals - Comprehensive Veterinary Information** Definitions and Terminology: • Babesiosis: A disease caused by Babesia spp., transmitted by ixodid ticks, affecting various mammals, including cattle, horses, sheep, goats, pigs, dogs, and cats. Causative Agents: • Pathogens: Various Babesia species, e.g., B. bovis, B. bigemina in cattle; B. canis, B. gibsoni in dogs. Physiopathology: • Transmission: Tick bites, transovarial transmission in ticks. • Pathogenesis: Intraerythrocytic protozoan parasites cause erythrocyte destruction, leading to anemia, hemolysis, and potential organ damage. Clinical Findings: • Symptoms: Fever, anemia, jaundice, hemoglobinuria, lethargy, weight loss, and in severe cases, CNS involvement. • Postmortem Lesions: Enlarged spleen, swollen liver, congested kidneys, and general anemia. Diagnosis: • Tests: Blood smear microscopy, PCR assays, serologic tests. • Microscopic Examination: Identification of parasites in erythrocytes. Treatment: • Babesiacides: Imidocarb dipropionate (1.2 mg/kg SC), diminazene aceturate (3.5 mg/kg IM). • Supportive Care: Anti-inflammatories, corticosteroids, fluid therapy, blood transfusions. Control and Prevention: • Tick Control: Acaricides, resistant breeds, management practices. • Vaccination: Live attenuated vaccines in some countries.

Answer 6

Answer: **Oxytetracycline** Explanation The correct answer is oxytetracycline. The cow has Anaplasmosis, a rickettsial organism that is transmitted by ticks. Infected calves have a low mortality rate, but adult cattle have a 20-50% mortality rate with this disease.

Answer 7

Answer: **Selenium deficiency** The correct answer is selenium deficiency. The pale muscle and clinical signs are classic for vitamin E and selenium deficiency. This is important to remember! Other things that should be on your differential list for this case include cardiotoxic plants. **Nutritional Myopathies in Ruminants and Pigs: Comprehensive Information** Nutritional Myodegeneration (NMD) Definition: Acute, degenerative disease of cardiac and skeletal muscle due to selenium or vitamin E deficiency in young, rapidly growing animals. Causative Agents: • Selenium Deficiency: More critical than vitamin E deficiency. • Vitamin E Deficiency: Common in animals fed poor-quality hay or straw. Clinical Signs: • Cardiac Muscle: Respiratory distress, arrhythmias, sudden death. • Skeletal Muscle: Muscle weakness, stiffness, difficulty rising, respiratory distress, dysphagia. Diagnosis: • Laboratory Tests: Increased CK, AST, LDH levels. • Definitive Diagnosis: Low selenium in blood/liver, low vitamin E in plasma. Treatment: • Injectable Selenium: 0.055–0.067 mg/kg IM or SC. • Vitamin E Supplements: Oral supplementation, injectable products with 300-500 IU vitamin E/mL. Prevention: • Dietary Management: Selenium supplementation in feed, periodic injections, high-quality forage. Hypokalemic Myopathy Definition: Severe muscle weakness due to low serum potassium (< 2.0 mmol/L) in dairy cattle, often associated with isoflupredone acetate administration. Clinical Signs: Weakness, recumbency, abnormal head/neck position, rumen hypomotility, anorexia, tachycardia. Diagnosis: Clinical signs, serum potassium < 2.0 mmol/L, increased CK and AST. Treatment: Potassium chloride supplementation, addressing primary cause of ketosis and anorexia. Nutritional Myopathy of Pigs Specific Conditions: Mulberry heart disease, hepatosis dietetica. Causative Agents: Selenium or vitamin E deficiency, iron dextran administration. Clinical Findings: • Mulberry Heart Disease: Sudden death, pericardial effusion, myocardial necrosis. • Hepatosis Dietetica: Subcutaneous edema, serous cavity transudate, liver necrosis. Diagnosis: History, clinical signs, necropsy, histology, serum/tissue selenium and vitamin E levels. Treatment: Selenium and vitamin E supplementation, injections to affected pigs and sows in late gestation.

Answer 8

Answer: **Fusobacterium necrophorum** Explanation The image shows widespread severe liver abscesses caused by Fusobacterium necrophorum. Fusobacterium necrophorum is a gram-negative, obligate anaerobic bacterium that is a component of normal rumen microflora. In this case, the metritis caused bacteremic spread of the organism which can go to the liver and release local toxins leading to damage and potential abscess formation. Typical Fusobacterium lesions are yellow and spherical with irregular outlines. A diagnosis could be confirmed in this case by culture of the uterine contents and liver. Affected livers are condemned at slaughter. Adhesions to surrounding organs or the diaphragm may require carcass trimming. Liver abscess can also lead to disease associated with thrombosis of the vena cava. The utility of prophylactic antibiotic therapy in large animal practice is unclear and this practice is often questioned with respect to cost, food safety (milk and meat withdrawal periods), and selection for antibiotic resistance in certain bacterial species. However, in this particular case, prophylactic antibiotics after replacement of the uterine prolapse may have prevented/cleared the uterine infection and/or prevented the bacteremia seeding the liver with fatal consequences. Fasciola hepatica is the liver fluke of cattle. While Fasciola can cause liver lesions, the lesions typically appear more as tracks and/or hemorrhage. Animals with fasciolosis typically present with abdominal pain or jaundice acutely. Chronically, animals become anemic or anorectic. Clostridium chauvei is the cause of blackleg in cattle and sheep and causes lameness and fever. Mycobacterium paratuberculosis is the cause of Johne's Disease which results in chronic wasting. *The liver condition in this case is caused by *Fusobacterium necrophorum*, a gram-negative anaerobic bacterium that can spread through bacteremia from metritis, resulting in liver abscesses. These abscesses are typically yellow, spherical, and irregular. Diagnosis is confirmed by culturing uterine contents and liver samples. Prophylactic antibiotics might have prevented this bacteremia after the uterine prolapse. Other liver-affecting conditions like *Fasciola hepatica* or *Clostridium chauvei* cause different lesions and clinical signs.* **Key Information on Vena Caval Thrombosis and Metastatic Pneumonia in Cattle** Etiology • Primary Cause: Ruminal acidosis leading to rumenitis and liver abscessation, with potential for thrombus formation in the caudal vena cava. • Bacteria Involved: Fusobacterium necrophorum, Trueperella pyogenes, staphylococci, streptococci, Escherichia coli. Clinical Findings • Acute Signs: Respiratory distress. • Chronic Signs: Weight loss, chronic coughing, tachypnea, tachycardia, hemic murmurs, coughing, pale mucous membranes, increased lung sounds, hemoptysis, and epistaxis. Diagnosis and Lesions • Diagnosis: Clinical signs, history, and postmortem examination. • Post-Mortem Lesions: Thrombus in the vena cava, hepatic abscesses, suppurative pneumonia with multifocal abscesses and aneurysms. Treatment and Control • Treatment: Antimicrobial therapy is usually ineffective; focus on supportive care. • Control: Nutritional management, gradual adaptation to high-grain diets.

Answer 9

Anwer: **Failure of omasal transport** Explanation The correct answer is failure of omasal transport, a form of vagal indigestion, which leads to an accumulation of fluid and some dorsal gas in the rumen, lack of motility, and inappetance. TRP is a common cause of vagal indigestion; the negative grunt test for xiphoid pain is the result of chronicity and formed adhesions that are no longer acutely painful. It is difficult to clinically distinguish between omasal transport failure and pyloric outflow failure, except that the latter usually has more profound acid-base and electrolyte disturbances, and the cow will appear sicker as a result. Abomasal torsion can be immediately ruled out because there is no abomasal ping on the right. In addition, if it were a right displaced abomasum, the cow would be showing more signs of distress and systemic disease such as episcleral injection and an elevated heart rate. Left displaced abomasum can be ruled out because the ping is monotone (LDA ping is variable in pitch) and the ping extends all the way back to the hip. Further, the large fluid filled rumen is rectally palpable, whereas a cow with LDA would have an empty rumen. Grain overload (rumen acidosis) would have a large fluid filled rumen, but the cow would be very sick with scleral injection and rapid heart rate. ***PowerLecture: Vagal Indigestion *The most likely diagnosis for this Holstein heifer is failure of omasal transport, a form of vagal indigestion. This condition leads to fluid accumulation, dorsal gas in the rumen, lack of motility, and inappetence. Omasal transport failure and pyloric outflow failure are hard to distinguish clinically, but the latter usually causes more severe electrolyte imbalances and systemic illness. Abomasal torsion, left displaced abomasum, and grain overload are ruled out due to the monotone ping, fluid-filled rumen, and absence of severe systemic signs.*

Answer 10

Answer: **Poloxalene orally (44 mg/kg)** Explanation You need to treat with a substance to reduce the surface tension and destabilize the froth. The pH is within normal limits for rumen contents; therefore, oral bicarbonate is not beneficial. In a pinch, one could also use cooking oil to attempt to break down the foam. *To treat the cow's frothy bloat, administer poloxalene orally at 44 mg/kg. This substance reduces surface tension, helping to destabilize and break down the foam. Since the rumen pH is normal at 6.2, oral bicarbonate is not useful. Cooking oil can be used as an alternative in emergencies.*

Answer 11

Answer: **Failure of passive transfer (FPT) and sepsis, with hypopyon** Explanation The history of a neonate with these signs and an elevated temperature, scleral injection and hypopyon are indicative of bacterial sepsis, a result of FPT.

Answer 12

Answer: **Treat all animals with tetracycline to eliminate carriers and regularly vaccinate all cattle against this serovar** Explanation Since Hardjo-Bovis is carried by cattle, he needs to both treat and vaccinate. Vaccination can prevent new carriers, but will not eliminate existing carriers. To be cost effective, he may need to mass treat dry cows and young stock using long acting tetracycline. Swine (and opossums, skunks and raccoons) are carriers of Pomona, dogs of Canicola, rats of Icterohemorrhagiae, swine, mice and horses of Bratislava, and raccoons, muskrats and squirrels of Grippotyphosa.

Answer 13

Answer: **Clostridium hemolyticum (Cl novyi type D)** Explanation The correct answer is *Clostridium hemolyticum*, now more properly called Cl novyi type D, which causes bacillary hemoglobinuria. The organism resides in the liver until anaerobic conditions develop, and then they start replicating and producing toxins. The finding of an anemic infarct on necropsy is classic for red water disease. Liver flukes are often associated with the disease, as they cause the anaerobic tracts needed for the organism to bloom. Marshy areas with snails are part of the liver fluke cycle of transmission. Anaplasmosis is not a good answer choice because there is no hemoglobinuria associated with the disease. The same goes for Salmonella. Leptospirosis is a good differential given the history; however, necropsy findings are consistent with bacillary hemoglobinuria. ***PowerLecture: Flukes and Bacillary Hemoglobinuria

Answer 14

Answer: **Vesicular stomatitis (VS)** Explanation VS occurs as an epidemic about once every 7 to 10 years in the western US. It appears to be spread by insect vectors and then spreads by contact and fomites from cow to cow once clinical disease occurs. Horses can also be affected by this virus. ***PowerLecture: Vesicular Stomatitis

Answer 15

Answer: **Replace the liner every 25 milkings** Explanation The incorrect answer is to replace the liner after 25 milkings. This is the best answer because the liner will last for at least 500 milkings. There are three types of liners: synthetic rubber, natural rubber, and silicone. These are designed to last anywhere between 500 and 10,000 milkings. Post-milking teat disinfection is probably the most effective way of reducing the rate of contagious mastitis. Pre-milking dip will help control environmental mastitis.

Answer 16

Answer: **Raise heifers in the foothills and put pregnant heifers in the hills only when 6 months or more pregnant** Explanation After decades of research, a novel deltaproteobacterium was identified as the causative agent of EBA in 2005. The disease is transmitted by a ground-dwelling soft tick, Ornithodoros coriaceus. Abortion occurs more than 3 to 4 months after exposure, so keeping pregnant heifers out of the foothills until they are 6 months pregnant means they calve before fetal lesions occur. Raising heifers in the foothills until breeding does provide premunition immunity. Also, the rancher should keep these heifers that abort, as they will now be immune to EBA. Tick control is very difficult on cattle running in the hills, but the ticks do not inhabit irrigated pastures (they live in the dry ground duff of needles and leaves), so bred heifers can be kept in irrigated pastures for months 1-6 of pregnancy. Feeding tetracycline for 9 months is not practical. As of 2019, there is no commercially available vaccine. However, since 2009 the University of California at Davis has been doing field trials on a live bacteria vaccine that has shown promising efficacy.

Answer 17

Answer: **Lupine** Explanation Some lupines contain alkaloids called sparteine and anagyrine. Cows eating lupine during early gestation often give birth to calves with cleft palates, crooked legs and distorted/malformed spines. Six of the poisonous species implicated in "crooked calf disease" are silky lupine (L. sericeus), tailcup lupine (L. caudatus), velvet lupine (L. leucophyllus), silvery lupine (L. argenteus), lunara lupine (L. formosus), and yellow lupine (L. sulphureus).

Answer 18

Answer: **4, 8, 4, 15** Explanation The correct answer is 4, 8, 4, and 15. Remember that xylazine is extremely potent in cattle, taking 10% of the dose that would be given to a horse of equivalent size is sufficient. Tolazoline is an alpha 2 antagonist. Give the same volume as xylazine. Lidocaine is commonly used during c-sections in cattle. If a producer is doing a c-section as a salvage procedure, it is important to inform that person that the cow cannot go to slaughter for 4 days. Visit www.farad.org to search for this type of information. Meloxicam is being used more and more. It is longer acting (~ 4 days) than banamine, but banamine only has 4 days of meat withdrawal. If you plan on going into production medicine, it is important to memorize the numbers for these commonly used drugs so that you can inform the producer.

Answer 19

Answer: **Keep dogs and coyotes away from cows and cow feed** Explanation The canine is the definitive host and sheds oocysts in the feces, which cause the disease when consumed by cattle. Like cattle, deer may also be infected as intermediate hosts. The dogs are initially infected by eating infected tissues from the cattle, most commonly an aborted fetus.

Answer 20

Answer: **Few if any overt signs** Explanation Unlike the bitch, who shows overt signs, including polydypsia, polyuria, inappetence, and sometimes high fever and diarrhea, the cow shows very few external signs of pyometra. Cows localize the problem to the uterine lumen. Diagnosis in cows is obtained by transrectal palpation or transrectal ultrasonography.

Answer 21

Answer: **Ostertagia ostertagii** Explanation This is a description of *type Il ostertagiasis*. The other parasites listed could be differentials with the exception of Dictyocaulus which is a lungworm. The main reason that Ostertagia is the best answer is the description of the abomasum. The cobblestone appearance which is also sometimes described as having a Moroccon leather appearance is essentially pathognomonic for Ostertagia. This occurs because Ostertagia larva undergo hypobiosis (larval inhibition) and lay dormant in the early fourth larval stage within the glands of the abomasum, forming the nodules. They resume development and emerge seasonally leading to severe signs.

Answer 22

Answer: **Malignant catarrhal fever (MCF)** Explanation *Malignant catarrhal fever (MCF)* in North America is caused by sheep-associated ovine herpesvirus-2. A very high percentage of sheep and goats in North America are infected with OHV-2 and can transmit the virus to susceptible cattle, bison, deer, and other related species, even if only in close proximity and not in direct contact. The virus causes lymphocytic vasculitis and can be fatal. BVD does cause fever, but uncommonly results in corneal opacity. The marked lymphadenopathy and lymphocytic vasculitis are not consistent with BVD. **PowerLecture: Malignant Catarrhal Fever - MCF

Answer 23

Answer: **Copper deficiency** Explanation The correct answer is copper deficiency. The giveaway is achromotrichia or loss of hair color. Dilution of the coat color is due to dysfunction of tyrosinase which converts L-tyrosine to melanin. In addition, copper deficient animals will have spontaneous fractures, secondary respiratory disease, diarrhea, ill thrift, decreased immunity, anemia, and poor reproduction. Selenium deficiency and BVD are actually pretty good differentials and if achromotrichia was not present either of those two are reasonable choices. Molybdenum deficiency would not result in achromotrichia. On the other hand, if there had been excess molybdenum, then the Cu:Mo ratio would be off and copper deficiency could be observed.

Answer 24

Answer: **Flunixin meglumine** Explanation *Flunixin meglumine* is **contraindicated** in this case. This drug (aka Banamine) is a non-steroidal anti-inflammatory drug (NSAID) and will only promote more ulceration because NSAIDs decrease mucosal blood flow. Blood transfusions are sometimes given if the bleeding is severe. Omeprazole (a hydrogen pump blocker) and ranitidine can be beneficial in calves and raise the abomasal pH, but not useful orally in adults. In adults, IV ranitidine can be used but is very expensive and reserved for high-value animals. **PowerLecture: Abomasal Ulcers

Answer 25

Answer: **Surgically reset the intussusception** Explanation Hopefully you will be able to recognize that the "mass" visualized in this image is an intussusception. After removal, an end-to-end anastomosis of the intestine is performed, and the cow is aggressively treated with antimicrobial drugs and IV fluids with a good content of chloride, such as saline, since these animals are usually suffering from hypochloremic hypokalemic metabolic alkalosis. ***PowerLecture: Colic

Answer 26

Answer: **Traumatic reticuloperitonitis** Explanation This question provided a classic description of the presentation for TRP. The clinical signs can be vague and misleading, but the localization of xiphoid pain as shown with the scooch test is a strong indicator of TRP. With a positive scooch test, the cow will be stiff, reluctant to scooch down, and grunts may be heard. Sometimes the stethoscope needs to be placed over the trachea because the grunt may be soft. Additionally, the xiphoid region should be pushed up upon to see whether the cow reacts painfully. There is no mention of pinging that would indicate a displaced abomasum. Xiphoid pain would not be seen as a result of grain overload. Cows with bovine spongiform encephalopathy (mad cow disease) will show neurologic clinical signs such as hypermetric ataxia, hyperexcitability, and hyperesthesia. **PowerLecture: Traumatic Reticuloperitonitis

Answer 27

Answer: **Amprolium** Explanation A number of drugs can be used to treat or prevent coccidiosis. The treatment dosage is generally higher but for fewer days than the preventive dosage. Monensin- and sulfa-containing drugs are also frequently used as treatments.

Answer 28

Answer: **Classical swine fever** Explanation CSF, also known as hog cholera, is very closely related to BVD and Border Disease viruses. It is currently of major importance in Central and South America, Eastern Europe, and Southeast Asia. ***PowerLecture: Foreign Animal Diseases

Answer 29

Answer: **Pyrrolizidine alkaloid toxicosis** Explanation PAs inhibit mitosis of hepatocytes, so they cannot multiply. As they age, they become large (megalocytes) and when they die they are replaced by fibrous tissue. Bile ducts proliferate as a nonspecific response to hepatic damage. You then look at some of the older alfalfa bales he was feeding to these calves and find loads of Senecio vulgaris, a PA containing plant. Aflatoxins (a mycotoxin) from Aspergillus and other fungi can cause liver lesions that are similar, but most pathologists think that finding megalocytes is diagnostic for PA toxicity. ***PowerLecture: Hepatic Disorders *The diagnosis is pyrrolizidine alkaloid (PA) toxicosis. PAs inhibit hepatocyte mitosis, leading to large megalocytes, fibrosis, and bile duct proliferation. The calves likely consumed *Senecio vulgaris*, a PA-containing plant found in their alfalfa feed. While aflatoxins can cause similar liver lesions, megalocytes are considered diagnostic for PA toxicity.* **Comprehensive Information on Pyrrolizidine Alkaloidosis in Animals** 1. Definitions: • Pyrrolizidine Alkaloidosis (PA): Chronic toxicosis leading to hepatic failure due to ingestion of toxic plants containing pyrrolizidine alkaloids. 2. Causative Agents: • Plants: Senecio, Crotalaria, Heliotropium, Amsinckia, Echium, Cynoglossum, Trichodesma. • Toxins: Pyrrolizidine alkaloids (e.g., jacobine, retrorsine, seneciphylline, monocrotaline). 3. Pathophysiology: • Absorption and Distribution: Absorbed via GI tract, distributed to liver via portal vein, also found in fetal tissues, milk, and eggs. • Metabolism: Converted to pyrroles in the liver, causing cytotoxic effects, particularly in hepatocytes. • Mechanism of Action: Pyrroles create DNA and nucleoprotein adducts, leading to antimitotic effects and megalocytosis, promoting hepatic neoplasms. 4. Clinical Findings: • Acute: Sudden death from hemorrhagic hepatic necrosis and visceral hemorrhages. • Chronic: Loss of condition, anorexia, dullness, diarrhea, icterus, ascites, photosensitization, hepatic encephalopathy (head-pressing, wandering, aggressive behavior), pica. • Lesions: Enlarged, hemorrhagic liver in acute cases; atrophied, fibrous, nodular liver in chronic cases. 5. Diagnosis: • Clinical Signs: Based on exposure history, clinical signs, and biochemical changes (elevated GGT, GDH). • Laboratory Tests: Chemical analysis of blood for toxic metabolites, hepatic biopsy showing megalocytosis and fibrosis. • Postmortem Examination: Histopathologic changes in liver, pulmonary, or renal tissues, hepatic tissue assays for pyrrolic metabolites. 6. Treatment: • Supportive Care: Hydration, managing photosensitization. • Diet: High-carbohydrate rations to avoid protein-induced clinical signs. • Prognosis: Poor for animals showing clinical signs; prevent further intake of toxic plants. 7. Control and Prevention: • Feed Management: Avoid feeding contaminated hay, silage, or pellets. • Biological Control: Use of sheep for grazing control, biological agents like predator moths and flea beetles. • Herbicide Application: Annual applications in spring to control toxic plants.

Answer 30

Answer: **Supplemental oxygen** Explanation The answer is supplemental oxygen. Cyanide blocks cellular respiration and blocks oxidative transport. As a result, hemoglobin cannot release oxygen to the tissues and venous blood stays saturated with oxygen and is bright red. Supplemental oxygen is unlikely to change this. The other three options are the usual treatments for cyanide toxicity. *The least effective treatment for cyanide toxicity is supplemental oxygen. Cyanide blocks cellular respiration, preventing hemoglobin from releasing oxygen to tissues, causing venous blood to remain oxygen-saturated and bright red. Supplemental oxygen does not resolve this issue, while other treatments directly counter cyanide's effects on cellular respiration.*

Answer 31

Answer: **Cattle are affected with oral and foot lesions and horses are unaffected** Explanation The correct answer is cattle are affected with oral and foot lesions and horses are unaffected. Only cloven-hoofed animals are affected by FMD. Therefore, sheep and pigs are susceptible and horses remain unaffected. If lesions are observed in swine, it is important to differentiate FMD from swine vesicular disease. In cattle, it is important to differentiate FMD from vesicular stomatitis, bovine papular stomatitis, pseudocowpox, and bluetongue. Another point is that sheep will not be affected by vesicular stomatitis. *The most consistent situation for Foot-and-Mouth Disease (FMD) is when cattle show oral and foot lesions while horses remain unaffected. FMD affects only cloven-hoofed animals, including cattle, sheep, and pigs, while horses are not susceptible. Differentiation from vesicular diseases in swine and cattle is essential for accurate diagnosis.* **Comprehensive Information on Foot-and-Mouth Disease (FMD) in Animals** 1. Definitions: • Foot-and-Mouth Disease (FMD): A highly contagious viral disease affecting cloven-hoofed animals, causing vesicular lesions. 2. Causative Agent: • Foot-and-Mouth Disease Virus (FMDV): An Aphthovirus from the family Picornaviridae with 7 serotypes: O, A, C, Asia 1, SAT 1, SAT 2, and SAT 3. 3. Epidemiology and Transmission: • Hosts: Cattle, pigs, sheep, goats, and over 70 species of wild artiodactyls. • Transmission: Direct contact, aerosolized particles, contaminated feed, fomites, and mechanical vectors. • Geographical Distribution: Endemic in Africa, the Middle East, and Asia; eradicated from North America and Europe. 4. Pathophysiology: • Primary Infection Sites: Pharyngeal mucosa, respiratory tract, skin lesions. • Viral Spread: Via lymphatic system, causing vesicle formation in the mouth, muzzle, teats, and feet. 5. Clinical Signs: • Cattle: Fever, vesicles in the mouth and on feet, drooling, lameness, weight loss, decreased milk yield, secondary bacterial infections. • Pigs: Fever, lameness, vesicles on the feet and snout, lethargy, loss of appetite. • Sheep/Goats: Largely inapparent; lameness, vesicles on feet and mouth. • Young Animals: Myocarditis leading to sudden death without vesicular lesions. 6. Diagnosis: • Laboratory Tests: RT-PCR, virus isolation, serology, antigen ELISA. • Samples: Vesicular epithelium or fluid, oropharyngeal fluid, serum. 7. Treatment: • No Specific Treatment: Supportive care in endemic regions. 8. Control and Prevention: • Culling: In FMD-free regions to control outbreaks. • Vaccination: Inactivated virus vaccines, particularly in endemic areas. • Biosecurity Measures: Strict movement controls, disinfection, and rapid reporting of outbreaks. Medications and Doses: • Supportive Care: Fluids, antipyretics, antibiotics for secondary infections as necessary. • Vaccination: Regular booster doses based on regional epidemiology and serotype prevalence. Summary: • Causative Agent: Foot-and-Mouth Disease Virus (FMDV). • Symptoms: Vesicles, fever, drooling, lameness, myocarditis in young animals. • Diagnosis: RT-PCR, virus isolation, serology. • Treatment: Supportive care. • Control: Vaccination, culling in non-endemic areas, biosecurity measures.

Answer 32

Answer: **Fetus infected before 125 days of gestation** Explanation The correct answer is fetus infected before 125 days of gestation, with most of those occurring before 100 days. A fetus infected with BVD at any time during gestation can be aborted or be a stillbirth. Most congenital defects associated with BVD occur when a fetus is infected between days 90-150 of gestation. Persistent infection of fetuses is seen when they are infected before 125 days of gestation. This is of importance because they have a potential to affect many other herdmates since they shed virus but may show no clinical signs. About half of the persistently infected calves will die during their first year of life. Clinical signs in BVD carriers vary greatly. They may range from an asymptomatic animal to one that has diarrhea, fever, pneumonia, and oral ulcerations. Additionally, you may have infected animals that are just repeat breeders. You may also see abortions, stillbirth, and congenital anomalies, The most co and congenital anomalies. The most common congenital anomaly associated with BVD is cerebellar hypoplasia, but there are many others. ***PowerPage: Bovine Viral Diarrhea ***PowerLecture: Bovine Viral Diarrhea *A fetus infected with the noncytopathic form of bovine viral diarrhea (BVD) before 125 days of gestation, particularly before 100 days, is most likely to become persistently infected. These fetuses shed the virus and may remain asymptomatic, but can infect herdmates. Persistent infection is significant due to potential transmission within the herd. Common congenital anomalies, like cerebellar hypoplasia, occur when infection happens between 90-150 days.* **Comprehensive Information on Bovine Viral Diarrhea (BVD) for NAVLE Preparation** Definition & Etiology: • Bovine Viral Diarrhea (BVD): A disease caused by Bovine viral diarrhea virus (BVDV), a Pestivirus in the Flaviviridae family. • Transmission: Mainly through direct contact with infected animals or contaminated fomites. Vertical transmission can lead to persistently infected (PI) calves. Pathophysiology: • BVDV can cause immunosuppression, leading to secondary infections. • Cerebellar Hypoplasia: In utero infection during mid-gestation can result in cerebellar hypoplasia in calves, characterized by ataxia, tremors, and inability to stand properly. Clinical Signs: • Diarrhea, fever, nasal discharge, immunosuppression, and mucosal disease in PI animals. • Neurological signs in calves with cerebellar hypoplasia include ataxia, intention tremors, and hypermetric gait. Diagnosis: • PCR and virus isolation are used to detect BVDV. • Serology to identify antibodies in the dam or calf. Prevention: • Vaccination: Prophylactic vaccination of breeding animals is essential to prevent vertical transmission and cerebellar hypoplasia in calves. Treatment: • No specific antiviral treatment; focus on supportive care and prevention of secondary infections.

Answer 33

Answer: **Branched-chain ketoacid decarboxylase** Explanation The correct answer is branched-chain ketoacid decarboxylase, which will cause accumulation of 2-keto-3-methylvaleric, 2-ketoisocaproic, and 2-isovaleric acids along with their precursors isoleucine, leucine, and valine. These are excreted in the urine and result in a burnt maple syrup smell (hence the name of the disease). This hereditary disease causes an encephalopathy. Acetyl-CoA carboxylase turns acetyl-CoA into malonyl CoA in fatty acid synthesis. Carnitine acyl translocase helps bring fatty acids across the inner mitochondrial membrane for degradation. Pyruvate kinase turns phosphoenol-pyruvate into pyruvate in the glycolysis pathway. *Maple syrup urine disease is caused by a deficiency in the enzyme branched-chain ketoacid decarboxylase, leading to the accumulation of 2-keto-3-methylvaleric, 2-ketoisocaproic, and 2-isovaleric acids, along with their precursors isoleucine, leucine, and valine. This results in the characteristic burnt maple syrup smell in the urine and causes encephalopathy in affected Hereford and polled Shorthorn calves.*

Answer 34

Answer: **Bacillary hemoglobinuria; penicillin, vaccination, and fluke control** Explanation The diagnosis is bacillary hemoglobinuria caused by Clostridium novyi type D (formerly called Cl. hemolyticum). Penicillin can be given to any animal showing early signs. Vaccination with Cl. novyi type D vaccine is effective, and prevention should also include fluke control. Migrating flukes cause hepatic damage and anaerobic areas which results in germination of the Cl. novyi spores in the liver, an infarct, and production of the hemotoxin. Flukes are best controlled by controlling snails in wet areas, fencing off wet areas, and using routine fluke treatments. *The diagnosis is bacillary hemoglobinuria, caused by *Clostridium novyi* type D. Treatment includes administering penicillin to affected animals. Prevention involves vaccination with *Cl. novyi* type D and fluke control. Fluke migration creates anaerobic liver areas, allowing *Cl. novyi* spore germination, leading to hepatic infarcts and hemotoxin production. Controlling snails, fencing wet areas, and routine fluke treatments are essential preventive measures.* **Bacillary Hemoglobinuria in Animals - Comprehensive Veterinary Information** Definitions and Terminology: • Bacillary Hemoglobinuria (Red Water Disease): Acute toxemia caused by Clostridium haemolyticum. Causative Agents: • Pathogen: Clostridium haemolyticum (also known as Clostridium novyi Type D). Physiopathology: • Transmission: Ingestion of spores, which remain latent in the liver and germinate under anaerobic conditions caused by liver damage (e.g., liver fluke infestation). • Pathogenesis: Spores germinate in the liver, producing beta toxin (phospholipase C) that causes intravascular hemolysis, leading to hemolytic anemia and hemoglobinuria. Clinical Findings: • Symptoms: Sudden onset of severe depression, fever, abdominal pain, dyspnea, severe diarrhea, and hemoglobinuria. Anemia, jaundice, and edema of the sternum may also be present. • Lesions: Liver infarcts, bloody fluid in body cavities, hemorrhagic intestines, dark friable kidneys, and purplish red urine in the bladder. Diagnosis: • Clinical Signs: Port wine-colored urine, severe depression. • Postmortem: Liver infarcts with diagnostic confirmation via PCR, IFAT, or other laboratory tests. Treatment: • Antimicrobials: High-dose penicillin or tetracyclines. • Supportive Care: Blood transfusions and fluid therapy. Control: • Vaccination: With C. haemolyticum bacterin, given once or twice yearly. • Management: Control of liver fluke infestation and improved pasture drainage.

Answer 35

Answer: **Cows remain relatively more alkalotic** Explanation DCAD is used to help prevent milk fever. Cows eating a DCAD diet are actually more acidotic which enhances parathyroid hormone function along with a better ability to utilize dietary calcium. The easy measure is to check urine pH (it should be acid) on cows to be sure they are ingesting the diet. To review, DCAD is dietary cation-anion difference. A DCAD diet is enhanced with more anionic salts containing the strong ions chloride and sulfur, and has decreased amounts of strong cations such as sodium and potassium. *A benefit of providing a DCAD diet to cattle is not that they remain more alkalotic; in fact, DCAD diets make cows slightly more acidotic. This enhances parathyroid hormone function and improves calcium utilization, helping to prevent milk fever. Urine pH should be monitored to confirm proper ingestion of the DCAD diet.* [Prevention of Parturition Paresis](https://www.merckvetmanual.com/metabolic-disorders/disorders-of-calcium-metabolism/parturient-paresis-in-cows?query=milk%20fever%20cattle#Prevention_v3282052)

Answer 36

Answer: **Methylene blue** Explanation Nitrate toxicosis causes methemoglobinemia, in which the blood appears chocolate brown. As a result, the oxygen carrying capacity and delivery is greatly reduced and the animal may die. Methylene blue is usually administered IV as a 1% to 4% solution, with a total dose of 4 to 15 mg/kg body weight to cattle, for treating nitrate toxicosis. Nitrates are found in high levels in many plants and some water sources. The nitrate is converted in the rumen to nitrite and then absorbed into the blood, which causes oxidation of the heme iron to the +3 ferric state (called methemoglobin). Methylene blue restores the iron in hemoglobin to its normal (reduced) oxygen-carrying state. This is achieved by providing an artificial electron acceptor for NADPH methemoglobin reductase (RBCs usually don't have one; the presence of methylene blue allows the enzyme to function at normal levels). The NADPH is generated via the hexose monophosphate shunt. *The most effective treatment for nitrate poisoning in cattle is intravenous administration of methylene blue. Nitrate toxicosis leads to methemoglobinemia, reducing oxygen-carrying capacity. Methylene blue, given as a 1-4% solution at 4-15 mg/kg, restores hemoglobin's oxygen-carrying ability by acting as an artificial electron acceptor for NADPH methemoglobin reductase.*

Answer 37

Answer: **Malignant cataral fever (MCF)** Explanation Malignant catarrhal fever (MCF) in North America is caused by sheep-associated ovine herpesvirus-2. A very high percentage of sheep and goats in North America are infected with OHV-2 and can transmit the virus to susceptible cattle, bison, deer, and other related species, even if only in close proximity and not in direct contact. The virus causes lymphocytic vasculitis and can be fatal. BVD does cause fever, but uncommonly results in corneal opacity. The marked lymphadenopathy and lymphocytic vasculitis are not consistent with BVD. ***PowerLecture: Malignant Catarrhal Fever - MCF *The most likely diagnosis is malignant catarrhal fever (MCF), caused by sheep-associated ovine herpesvirus-2 (OHV-2). This virus, common in sheep and goats, can transmit to cattle and cause fatal lymphocytic vasculitis. Key signs include corneal opacity, high fever, lymphadenopathy, and CNS symptoms. BVD is less likely as it rarely causes corneal opacity or marked lymphadenopathy.* **Comprehensive Information on Malignant Catarrhal Fever (MCF) in Animals** 1. Definitions: • Malignant Catarrhal Fever (MCF): A severe, often fatal, lymphoproliferative disease in ruminants caused by ruminant gammaherpesviruses. 2. Causative Agents: • Viruses: Ovine herpesvirus-2 (sheep), alcelaphine herpesvirus-1 (wildebeest), caprine herpesvirus-2 (goats). 3. Epidemiology: • Hosts: Cattle, water buffalo, bison, deer. • Transmission: Direct contact or aerosolized virus from carriers like sheep and wildebeest. • Seasonality: Linked to lambing/calving periods; virus shedding is higher in young animals. 4. Clinical Signs: • Acute Cases: Fever, depression, oral/nasal erosions, lymphadenopathy, corneal opacity. • Peracute Cases: Sudden death, hemorrhagic diarrhea, hematuria. • Chronic Cases: Alopecia, weight loss. 5. Pathophysiology: • Infection Mechanism: Viral replication in lymphoid tissues leading to widespread vasculitis. • Lesions: Necrosis and inflammation of mucosal epithelium, generalized lymphoid proliferation, vasculitis. 6. Diagnosis: • Clinical Signs: Fever, erosions, ocular changes, lymphadenopathy. • Laboratory Tests: PCR, immunohistochemistry, serology. • Differential Diagnoses: BVD, IBR, East Coast fever, rabies. 7. Treatment: • Supportive Care: No specific antiviral treatment; manage stress and secondary infections. • Prognosis: Grave; high mortality rate. 8. Control and Prevention: • Biosecurity: Separate carriers (sheep, wildebeest) from susceptible species. • No Vaccine: Early weaning and isolation of lambs. Medications and Doses: • Supportive Care: Antipyretics, fluids, antibiotics for secondary bacterial infections. Summary: • Causative Agents: Ruminant gammaherpesviruses. • Symptoms: Fever, nasal/oral erosions, lymphadenopathy, corneal opacity. • Clinical Changes: Vasculitis, necrosis, lymphoid proliferation. • Diagnosis: Clinical signs, PCR, serology. • Treatment: Supportive care. • Control: Biosecurity, no vaccine available.

Answer 38

Answer: **4 liters of intravenous fluids containing glucose, sodium, bicarbonate, chloride and lesser amounts of potassium** Explanation The calf is in metabolic acidosis (base deficit of about 15) and needs sodium containing fluids IV that contain bicarbonate or other base. 4 liters intravenously is a more appropriate fluid volume for a dehydrated 10-day old calf, calculated as 10% Of the 40 kg body weight. The sunken eye, as seen in the photo, is an important indicator of marked dehydration. To treat metabolic acidosis caused by loss of sodium containing fluids you need to give more sodium than chloride, so sodium bicarbonate is the fluid of choice. Neonates such as this one tend to develop severe metabolic acidosis as they dehydrate due to absorption of acids from the gut and due to loss of renal compensatory mechanisms due to poor renal perfusion. The calf is also likely to be hypoglycemic, so adding glucose is essential. As you rehydrate and bring up blood glucose, the serum potassium will be driven back into cells and needs to be replaced with some potassium in the fluids. ***PowerLecture: Calf Diarrhea Part 2 *The best treatment for this 10-day-old dehydrated Holstein calf is 4 liters of intravenous fluids containing glucose, sodium, bicarbonate, chloride, and potassium. The calf is in metabolic acidosis with a base deficit of about 15, requiring sodium bicarbonate to correct the acidosis. Adding glucose helps address likely hypoglycemia, and potassium replenishment is essential as rehydration drives potassium back into cells.*

Answer 39

Answer: **Oral propylene glycol** Explanation The oral propylene glycol will serve as a precursor for glucose production, and will help with the demands of lactation that are causing increased fat mobilization and ketosis. A fourth treatment that is sometimes used is corticosteroids, as they decrease milk production and increase gluconeogenesis. ***PowerPage: Ketosis *In addition to IV glucose and SQ insulin, the cow should receive oral propylene glycol. This acts as a glucose precursor, helping to meet the energy demands of lactation, reducing fat mobilization, and combating ketosis. Corticosteroids can also be used to decrease milk production and increase gluconeogenesis.*

Answer 40

Answer: **A 5-month old calf which was persistently infected as a fetus with a non cytopathic (nonCPE) biotype of BVD virus is superinfected with a cytopathic (CPE) biotype of BVD due to rearranging of the parent non-CPE viral RNA.** Explanation This is the correct answer because it describes the current understanding of the pathogenesis of both mucosal disease and chronic BVD. A 5-month old calf is infected with CPE biotype of BVD virus and then superinfected with a nonCE biotype of BVD virus is incorrect because it does not say that there was persistent fetal infection; also, the order of the superinfection is the reverse of what causes mucosal disease or chronic BVD. A 5-month old calf which was persistently infected with the nonCPE biotype of BVD virus as a fetus forms antigen-antibody complexes which cause a fatal immune-mediated disorder is incorrect because this is not the mechanism by which mucosal disease or chronic BVD occur. All other answer choices are incorrect because they each describe one of the acute clinical syndromes from primary infection, rather than either mucosal disease or chronic BVD. ***PowerPage: Bovine Viral Diarrhea *Mucosal disease or chronic Bovine Virus Diarrhea (BVD) occurs when a 5-month-old calf, persistently infected as a fetus with the non-cytopathic (nonCPE) biotype of BVD virus, is superinfected with the cytopathic (CPE) biotype due to rearrangement of the parent non-CPE viral RNA. This describes the current pathogenesis of both mucosal disease and chronic BVD.*

Answer 41

Answer: **Change feed and treat.** The correct answer is to change feed and begin treatment of the animals affected with woody tongue, as the response is often good. Sodium iodide and antibiotics are effective. Given the presentation and clinical signs, these animals have probably begun to ingest very rough and stemmed (scabrous) feed items that have injured their mouths. Upon injury, the normal inhabitant Actinobacillus lignieresii invades the soft tissues and causes the characteristic woody tongue granulomatous inflammation. These animals don't have rabies, and there is no need to cull them. Change feed before additional animals are affected. Do not use aminoglycosides as they have an extremely long withdrawal period.

Answer 42

Answer: **Hypoderma** Explanation The correct answer is Hypoderma bovis or H lineatum. Hypoderma is also known as the cattle grub, heel fly, or warble fly. The life cycle begins with the female attaching up to 500 eggs to the hairs around the hocks and lower portions of the cow. First-stage larvae will hatch in just a few days and burrow into the skin. At this point, they begin their tour de cow and migrate towards the epidural fat in the spinal canal(H bovis) or via the esophagus (H lineatum). After several months in this beautiful location, they become L2s and migrate to the subcutaneous tissues of the back where they will molt once more, and become L3s. Once they are L3s, the swelling on the cows' backs can be felt. After 5-11 weeks, the L3s mature and burst through the skin, dropping on the ground where they will become adults in another 1-3 months. Sarcophaga spp are known as the flesh flies. An adult female will deposit her eggs in wounds and ulcers; the larvae then feed off the wounds. Eventually, they mature into L3s and fall off to pupate on the ground. Simulium flies are also known as buffalo gnats or black flies. Adult females are the key problem with these flies because they suck blood! They prefer the legs, abdomen, head, and ears. Additionally, they will only eat during daytime. Female flies are an annoyance to cows and cause decreased productivity. Anopheles are just mosquitoes; however, they are the most important vectors of human malaria and spread West Nile Virus. Culicoides are also known as no-see-ums, biting midges, and punkies. They are a great annoyance to cows and have the potential to transmit bluetongue and Onchocerca. In horses, they are thought to be the cause of sweet itch, a Type I hypersensitivity to their saliva.

Answer 43

Answer: **Rumen Acidosis** Explanation Dairy cattle which are fed a high concentrate diet should be gradually introduced to it. Even so, an additional dietary buffer may be needed. The herd veterinarian should check rumen pH on about 5 high-producing cows by needle stick of the rumen 2 to 3 hours after they are fed. If some fall below pH 5.5, additional sodium bicarbonate should be added to the ration. The low rumen pH causes rumenitis allowing bacteria to translocate through the mucosa and be filtered from the hepatic portal circulation by the liver, resulting in one or more hepatic abscesses. The key to picking rumenitis is that there are many culled dairy cattle coming in with this problem of hepatic abscess. If it were feet or hardware it would only occasionally lead to a liver abscess. [Subacute Ruminal Acidosis in Cattle and Sheep](https://www.merckvetmanual.com/digestive-system/diseases-of-the-ruminant-forestomach/subacute-ruminal-acidosis-in-cattle-and-sheep?query=rumen%20acidosis%20in%20bovine)

Answer 44

Answer: **Actinomycosis** Explanation Also known as lumpy jaw, this condition results from the entry of the normal rumen inhabitant Actinomyces bovis into the bony mandible (usual site) or maxilla through a break in the mucous membranes or teeth. It may be arrested with therapy using sodium iodide, antimicrobials or even isoniazid off-label, but the bony swelling seldom changes much, even if arrested. ### Actinomycosis in Cattle, Swine, and Other Animals #### Definitions and Causative Agents: - **Actinomycosis**: A chronic bacterial infection caused by gram-positive, anaerobic bacteria *Actinomyces*. - **Causative Agents**: - *Actinomyces bovis*: Lumpy jaw in cattle. - *A. suis* (A. denticolens): Pyogranulomatous mastitis in swine. - *A. hordeovulneris*: Localized abscesses and systemic infections in dogs. - *A. viscosus*: Cutaneous abscesses, pneumonia, pyothorax in dogs. #### Clinical Findings: - **Cattle**: Slow-growing, firm mass attached to the mandible, facial distortion, loose teeth, dyspnea, ulceration, and fistulous tracts. - **Swine**: Pyogranulomatous mastitis, subcutaneous granulomatous lesions, lung and organ abscesses. - **Dogs**: Localized abscesses, pyogranulomatous pleuritis, peritonitis, and visceral abscesses. #### Diagnosis: - **Methods**: Clinical signs, culture (anaerobic conditions), Gram stain, radiology, cytology, and biopsy. #### Treatment: - **Ruminants**: Intravenous sodium iodide (70 mg/kg of a 10%-20% solution, repeated at 7-10 day intervals), with antimicrobials like penicillin, florfenicol, or oxytetracycline. - **Swine**: Rarely successful; surgical removal may be required. - **Dogs**: Surgical debridement, penicillin, cephalosporins, sulfonamides, and repeated chest drainage for pyothorax. #### Prevention: - **Cattle**: Avoid coarse, stemmy feeds or feeds with plant awns to prevent mucosal damage. For more detailed information, visit the [Merck Veterinary Manual - Actinomycosis in Cattle, Swine, and Other Animals](https://www.merckvetmanual.com/generalized-conditions/actinomycosis/actinomycosis-in-cattle,-swine,-and-other-animals).

Answer 45

Answer: **Acute bovine pulmonary edema and emphysema** Explanation This condition is an ARDS (acute respiratory distress syndrome) of cattle that usually occurs after animals are moved from poor quality feed to an improved lush pasture. The mechanism involves ingestion of L-tryptophan in lush feed being converted to 3-methylindole in the rumen. 3-MI is pneumotoxic and causes pulmonary edema, alveolar epithelial hyperplasia, hyaline membranes, and emphysema. Lesions of the other choices are different from the ones described here. The two bacterial pneumonias usually occur in younger, often confined and stressed, animals. BRSV tends to affect young calves peracutely, and would not cause signs as described in these 3 year-old animals. Lungworm infestation could have similar clinical signs but is unlikely to be this acute and severe in 3 year-old animals, and parasitic pneumonia has a great deal of coughing associated with it. The pathology would be different with more consolidation and bronchial exudates. **Pulmonary Emphysema, Edema, and Interstitial Pneumonia in Cattle** Definitions and Causative Agents: • Acute Bovine Pulmonary Emphysema and Edema (ABPEE): Also known as “fog fever”, caused by metabolites of L-tryptophan in lush pasture. • Pathogenesis: L-tryptophan is converted by ruminal microorganisms to 3-methylindole, which is pneumotoxic. Clinical Changes and Symptoms: • Symptoms: Mild to severe dyspnea, tachypnea, hyperpnea, mouth breathing, drooling, expiratory grunt, minimal coughing. • Lesions: Pulmonary edema, emphysema, alveolar epithelial hyperplasia, hyaline membrane formation. Diagnosis: • Assessment: History of pasture change, clinical signs, necropsy findings. • Histopathology: Congestion, alveolar edema, epithelial hyperplasia. Treatment: • No effective treatment: Manage affected animals with caution to prevent further stress and possible sudden death. Prevention: • Pasture Management: Gradual introduction to lush pastures, use of hay before grazing, strip grazing, grazing with less susceptible animals first. • Medications: Monensin or lasalocid to inhibit bacteria converting L-tryptophan to 3-methylindole. For detailed information, visit the Merck Veterinary Manual - Pulmonary Emphysema, Edema, and Interstitial Pneumonia in Cattle.

Answer 46

Answer: **Blood transfusion with fresh whole blood** Explanation The thrombocytopenia is caused by BVD virus adhering to thrombocytes which are then removed by the reticuloendothelial (RE) system. Once the number gets this low, fatal hemorrhage is possible at any moment. Although not usual, this form of BVD has been described. The other forms of therapy may be needed as well. If the calf survives, you will also need to determine whether or not he remains persistently infected with BVD... if he does, he should not be retained. **Comprehensive Information on Bovine Viral Diarrhea (BVD) for NAVLE Preparation** Definition & Etiology: • Bovine Viral Diarrhea (BVD): A disease caused by Bovine viral diarrhea virus (BVDV), a Pestivirus in the Flaviviridae family. • Transmission: Mainly through direct contact with infected animals or contaminated fomites. Vertical transmission can lead to persistently infected (PI) calves. Pathophysiology: • BVDV can cause immunosuppression, leading to secondary infections. • Cerebellar Hypoplasia: In utero infection during mid-gestation can result in cerebellar hypoplasia in calves, characterized by ataxia, tremors, and inability to stand properly. Clinical Signs: • Diarrhea, fever, nasal discharge, immunosuppression, and mucosal disease in PI animals. • Neurological signs in calves with cerebellar hypoplasia include ataxia, intention tremors, and hypermetric gait. Diagnosis: • PCR and virus isolation are used to detect BVDV. • Serology to identify antibodies in the dam or calf. Prevention: • Vaccination: Prophylactic vaccination of breeding animals is essential to prevent vertical transmission and cerebellar hypoplasia in calves. Treatment: • No specific antiviral treatment; focus on supportive care and prevention of secondary infections.

Answer 47

Answer: **Freemartin** Explanation The correct answer is that this calf is a freemartin. This is evident by the clinical signs provided. A freemartin results from in utero exposure of the female to Mullerian-inhibiting hormone (also called anti-mullerian hormone or AMH) being secreted by the male. She is exposed via anastomosis between the two fetuses' chorioallantoic vessels. Lupine causes fetal arthrogryposis if ingested, and ponderosa pine needles induce late abortion if consumed. **Freemartin Heifer and Blood Types** Freemartinism in Cattle Freemartinism is a condition of sterility observed in female cattle (heifers) that are born as twins to male calves. Approximately 92% of such heifers are sterile. This condition arises due to the vascular connections between the placentas of the twin fetuses, which allows the transfer of anti-Müllerian hormone from the male to the female fetus. This hormone inhibits the development of the female reproductive tract, leading to varying degrees of masculinization of the female genitalia. Characteristics of Freemartin Heifers • Genitalia: Affected heifers typically have a short vagina that ends blindly, without communication with the uterus. The cervix is often absent, and the ovaries usually remain underdeveloped and small. • Reproductive Organs: The tubular genital organs may range from cord-like structures to near-normal uterine horns, depending on the extent of masculinization. Diagnostic Criteria • Vaginal Length: In calves 1-4 weeks old, the normal vaginal length is 13-15 cm, whereas in freemartin heifers, it is about 5-6 cm. This can be measured by gently inserting a lubricated probe with a blunt end into the vagina. • Cytogenetic Examination: Freemartins typically exhibit a mix of XX and XY chromosome patterns due to the interchange of cells in the placental circulation between the fetuses. • Blood Types: Freemartinism can also be indicated by the presence of two different blood types in a single animal, reflecting the cellular exchange between the twin fetuses.

Answer 48

Answer: **Chorioallantoic membrane slip** Explanation The correct answer is chorioallantoic membrane slip. Placentomes will be palpable starting between 75-90 days of gestation. The fetus itself will be palpable beginning at approximately 60 days, but may be out of reach between months 4-7 of gestation. Uterine artery fremitus will be evident on the ipsilateral pregnant horn at about 120 days of gestation. From 7 months on, fremitus is palpable bilaterally. Fremitus does not necessarily indicate a viable pregnancy. *At approximately 30 days of gestation, the positive sign of pregnancy in a beef cow is the chorioallantoic membrane slip. Placentomes are palpable at 75-90 days, the fetus at 60 days, and uterine artery fremitus appears around 120 days, but fremitus doesn’t always indicate a viable pregnancy.*

Answer 49

Answer: **Epizotic bovine abortion** Explanation The correct answer is epizootic bovine abortion (EBA), also called foothill abortion. EBA is an important disease for beef producers in the foothill and mountainous regions of California, Northern Nevada and Southern Oregon. The lesions described in the question are consistent with this diagnosis. The etiologic agent of EBA is a bacteria, Pajaroellobacter abortibovis and the vector is a tick, Ornithodoros coriaceus. Tritrichomona foetus is involved with early embryonic death. Brucellosis abortions are rare since it has been almost completely eradicated from the U.S. Lesions include autolysis, placentitis, and bronchopneumonia. Infectious Bovine Rhinotracheitis (IBR) causes rapid fetal death; therefore, there is very little time for fetal response. Lesions you are likely to see include autolysis and focal necrosis of the organs. *The most likely cause of this abortion is epizootic bovine abortion (EBA), also known as foothill abortion. EBA occurs in foothill and mountainous regions of California, Northern Nevada, and Southern Oregon. The lesions described, such as enlarged lymph nodes, spleen, and chronic granulomatous infection, are consistent with EBA, caused by **Pajaroellobacter abortibovis** and transmitted by the tick **Ornithodoros coriaceus**.*

Answer 50

Answer: **Treat all animals with tetracycline to eliminate carriers and regularly vaccinate all cattle against this serovar** Explanation Since Hardjo-Bovis is carried by cattle, he needs to both treat and vaccinate. Vaccination can prevent new carriers, but will not eliminate existing carriers. To be cost effective, he may need to mass treat dry cows and young stock using long acting tetracycline. Swine (and opossums, skunks and raccoons) are carriers of Pomona, dogs of Canicola, rats of Icterohemorrhagiae, swine, mice and horses of Bratislava, and raccoons, muskrats and squirrels of Grippotyphosa. **Leptospirosis in Animals - Comprehensive Veterinary Information** Definitions and Terminology: • Leptospirosis: A zoonotic disease caused by pathogenic serovars of Leptospira. Causative Agents: • Pathogens: Leptospira interrogans, Leptospira borgpetersenii. Physiopathology: • Transmission: Direct or indirect contact with urine from infected animals, contaminated water, or soil. • Pathogenesis: Bacteria penetrate mucous membranes or broken skin, spread through the bloodstream, and localize in the kidneys, liver, lungs, and other organs. Clinical Findings: • Symptoms: Fever, anorexia, vomiting, dehydration, icterus, renal failure, hemolytic anemia, uveitis, abortion, stillbirths. • Lesions: Interstitial nephritis, hepatitis, pulmonary hemorrhage. Diagnosis: • Tests: Microscopic agglutination test (MAT), PCR, culture, ELISA. • Sample: Blood, urine, tissue samples. Treatment: • Antibiotics: Doxycycline, amoxicillin, penicillin. • Supportive Care: Fluids, blood transfusions. Prevention: • Vaccination: Polyvalent inactivated vaccines. • Hygiene: Avoid exposure to potentially contaminated environments.

Answer 51

Answer: **Treat all animals with tetracycline to eliminate carriers and regularly vaccinate all cattle against this serovar** Explanation Since Hardjo-Bovis is carried by cattle, he needs to both treat and vaccinate. Vaccination can prevent new carriers, but will not eliminate existing carriers. To be cost effective, he may need to mass treat dry cows and young stock using long acting tetracycline. Swine (and opossums, skunks and raccoons) are carriers of Pomona, dogs of Canicola, rats of Icterohemorrhagiae, swine, mice and horses of Bratislava, and raccoons, muskrats and squirrels of Grippotyphosa. **Leptospirosis in Animals - Comprehensive Veterinary Information** Definitions and Terminology: • Leptospirosis: A zoonotic disease caused by pathogenic serovars of Leptospira. Causative Agents: • Pathogens: Leptospira interrogans, Leptospira borgpetersenii. Physiopathology: • Transmission: Direct or indirect contact with urine from infected animals, contaminated water, or soil. • Pathogenesis: Bacteria penetrate mucous membranes or broken skin, spread through the bloodstream, and localize in the kidneys, liver, lungs, and other organs. Clinical Findings: • Symptoms: Fever, anorexia, vomiting, dehydration, icterus, renal failure, hemolytic anemia, uveitis, abortion, stillbirths. • Lesions: Interstitial nephritis, hepatitis, pulmonary hemorrhage. Diagnosis: • Tests: Microscopic agglutination test (MAT), PCR, culture, ELISA. • Sample: Blood, urine, tissue samples. Treatment: • Antibiotics: Doxycycline, amoxicillin, penicillin. • Supportive Care: Fluids, blood transfusions. Prevention: • Vaccination: Polyvalent inactivated vaccines. • Hygiene: Avoid exposure to potentially contaminated environments.

Answer 52

Answer: **There is no effect** Explanation The correct answer is that there is no effect when the cow is in anestrus. That is the problem with using PGF2-alpha to synchronize estrus cycles in cows. A mature corpus luteum is needed so that PGF2-alpha can lyse it; the cow goes back into estrus in about 2-5 days.

Answer 53

Answer: **Administer epidural anesthetic, remove attached fetal membranes, clean and lubricate the uterus and replace in normal position, then administer oxytocin and calcium gluconate** Explanation This is a case of uterine prolapse. Because images may sometimes be difficult to differentiate uterine versus other prolapses, the clinical history can be useful in helping differentiate which type of prolapse is likely. Uterine prolapse occurs immediately or within hours of parturition. Vaginal prolapse occurs primarily in late pregnancy. Rectal prolapse is typically associated with straining to defecate. The uterus is more easily replaced if the cow is standing. If she remains recumbent it may help to put her sternal and pull both hind legs into a position behind her. The oxytocin will help involute the uterus and expel fluids, and the calcium gluconate will help treat or prevent hypocalcemia. Do not give oxytocin before replacing the uterus because this makes it turgid and much more difficult to replace. Although not mentioned in any of the answer choices, administration of an antibiotic (i.e. oxytetracycline) may be useful to reduce metritis. If the cow remains down and unable to rise, she should be lifted using a flotation tank. The sooner this is done, the more likely she is to recover.

Answer 54

Answer: **At least 6 months** Explanation The correct answer is at least 6 months. Placentomes (cotyledons on the placenta / caruncules on the uterus) will be palpable starting between 75-90 days of gestation and at 150 days can reach the size of a half-dollar coin. Three or more placentomes must be palpated to rule out that you are not palpating an ovary. Uterine artery fremitus which is hypertrophy of the middle uterine artery with fluid turbulence that gives a "buzz" feeling to the artery will be evident on the ipsilateral pregnant horn at about 120 days of gestation. From 6-7 months on, the fremitus can be felt bilaterally. Fremitus is not a positive sign of pregnancy, but can be useful in staging.

Answer 55

Answer: **You suggest surgical removal and sexual rest for 2-3 weeks** Explanation Penile warts in young bulls are quite common and are caused by bovine papilloma virus-1 (BPV-1) which can also cause warts on the nose or teats. Warts are very contagious and primarily spread by contamination of facility equipment but also spread directly from bull to bull. BPV-1 infection is not associated with other health problems. The treatment of choice for penile warts is surgical removal. Surgical damage to the warts frequently stimulates an immune response against BPV-1. Healing is usually complete within 2-3 weeks. Autogenous vaccines have been used to treat penile warts but this is rarely practiced now due to cost and risk of severe reactions and relatively little benefit compared to surgical removal. It is not necessary to wait 6 months before breeding. Bulls typically reach puberty at 9-11 months of age depending on breed. Scrotal circumference of a 1 year-old bull also varies by breed but >30 cm is typically recommended for breeding at this age. *The best recommendation is surgical removal of the penile warts, followed by 2-3 weeks of sexual rest. Penile warts in young bulls, caused by bovine papilloma virus-1 (BPV-1), are common and highly contagious. Surgical removal typically triggers an immune response, leading to complete healing within 2-3 weeks. Autogenous vaccines are rarely used due to cost and risk, and it's unnecessary to delay breeding for six months. The scrotal circumference of 33 cm is acceptable for a 1-year-old bull, indicating readiness for breeding.*

Answer 56

Answer: **Anaplasmosis** Explanation The correct answer is Anaplasmosis, which is a cause of extravascular hemolysis. Pseudocowpox is a parapox virus and results in proliferative teat lesions. Vesicular stomatitis is a reportable disease caused by a rhabdovirus. It is reportable because it is similar in presentation to foot and mouth disease. Clinical signs include ulceration of the teats and mouth. Bluetongue and herpes mammillitis also result in ulcerative lesions.

Answer 57

Answer: **"Physiological abortion" attributable to twinning** Explanation In cattle, twinning is a significant risk factor for abortion. Brucella abortus can cause abortion, but there are typically signs of severe inflammation, including placentitis. IBR virus can quickly kill a bovine fetus, but as with Herpes viruses in many hosts, there are signs of severe inflammation throughout the fetus. Listeria monocytogenes can cause abortion, but the fetus is usually autolyzed to a significant extent, and there are often brain micro-abscesses present. Neosporum caninum can cause epidemic or enzootic patterns of abortion, but typically abortions occur earlier than 8 months and there is autolysis of tissues. Frequently, there are granulomas in the brain. Lethal white svndrome is a cause of death in foals. not abortion in cattle. *The most compatible diagnosis for the twin bovine abortion with no gross or histological lesions and negative serum immunoglobulins is "physiological abortion" due to twinning. Twinning significantly increases the risk of abortion in cattle. Other causes like **Brucella abortus**, IBR virus, **Listeria monocytogenes**, and **Neospora caninum** typically present with inflammation, autolysis, or organ lesions, none of which were observed here. Lethal white syndrome affects foals, not cattle.*

Answer 58

Answer: **Likely pregnant** Explanation The correct answer is that the cow is likely to be pregnant. If the progesterone levels were low on days 0, 21, and 24 of estrous, it is almost certain she is not pregnant. High progesterone levels throughout may indicate that she has been pregnant or that she has a persistent corpus luteum. In this scenario, with low levels initially at day O but high at day 21 and 24, this cow should be pregnant. *The cow is likely pregnant based on low milk progesterone levels on day 0 of estrous and high levels on days 21 and 24. Low progesterone throughout would indicate non-pregnancy, while high levels suggest pregnancy or a persistent corpus luteum. In this case, the hormonal pattern indicates pregnancy.*

Answer 59

Answer: **Push forward on the vagina while rolling the cow clockwise** Explanation The correct answer is push forward on the vagina while rolling the cow clockwise, which may seem counter-intuitive. By stabilizing the uterus and rotating the cow around it, you can attempt to relieve the torsion. *To address a clockwise uterine torsion, the recommended intervention is to push forward on the vagina while rolling the cow clockwise. This helps stabilize the uterus while rotating the cow, potentially relieving the torsion by allowing the uterus to untwist as the cow is rolled.*

Answer 60

Answer: **Transmission by the milker's hands and milking equipment** Explanation The correct answer is transmission by milker's hands and milking equipment. This is the main factor in the spread of mastitis, and you must work closely with your client in training personnel to apply proper milking techniques. ***PowerPage: Mastitis

Answer 61

Answer: **Utrecht pattern** Explanation The correct answer is the Utrecht pattern. This pattern achieves a nice mucosal and serosal seal when done correctly. Additionally, the exposure of suture to the serosa is minimized with this type of pattern, so adhesions of uterus to surrounding structures is minimized

Answer 62

Answer: **Intrauterine** Explanation Artificial insemination (Al) with frozen or fresh semen is nearly always performed intrauterine in both the mare and the cow. Conception rates are optimal, compared with intravaginal or intracervical routes of Al. With the intracervical and intravaginal routes, sperm will have farther to go to get to the site of fertilization (ampulla of oviduct), and won't have the advantage of being propelled towards the ampullae that sperm deposited intrauterine would have. Intravaginal routes result in very low conception rates unless sperm numbers are greatly increased, in which case one of the main advantages of Al (ability to dilute semen from a superior male and use it on several females) is lost. Given the same quality and quantity of semen/sperm, conception rates following intracervical routes of Al are higher than Al by intravaginal routes, but still much lower than when intrauterine routes are used. Intravestibular (i.e., just inside the vulva) will result in very low conception rates. Many sperm will be killed by urine, and the surviving sperm will have much farther to go to get to the site of fertilization. Al by the intra-abdominal route, i.e., via the oviducts, is highly impractical at this time, as the oviducts are not easily catheterized. *The preferred site for practical artificial insemination (AI) in both mares and cows is intrauterine. This method ensures optimal conception rates compared to intravaginal or intracervical routes, as it places sperm closer to the site of fertilization (ampulla of the oviduct). Intrauterine AI benefits from sperm being propelled towards the ampullae, increasing the chances of successful fertilization. Other methods, such as intravaginal or intravestibular, result in lower conception rates due to the distance sperm must travel and potential sperm damage.*

Answer 63

Answer: **Uterine tear** Explanation The correct answer is uterine tear. With a traumatic fracture or damage to nerves, the cow would have gone down right away rather than an hour later. Hypocalcemia is possible but less likely in this case where the calf had to be forcibly extracted which can result in a uterine tear, and would be unlikely to make her pale and tachycardic.

Answer 64

Answer: **PG2-alpha and dexamethasone** Explanation The correct answer is PGF2-alpha and dexamethasone. This is because at this point (5 to 8 months), both the CL and the fetus are involved in maintaining the pregnancy.

Answer 65

Answer: **Replace the liner every 25 milkings** Explanation The incorrect answer is to replace the liner after 25 milkings. This is the best answer because the liner will last for at least 500 milkings. There are three types of liners: synthetic rubber, natural rubber, and silicone. These are designed to last anywhere between 500 and 10,000 milkings. Post-milking teat disinfection is probably the most effective way of reducing the rate of contagious mastitis. Pre-milking dip will help control environmental mastitis. *The incorrect statement is "Replace the liner every 25 milkings." Liners last for at least 500 milkings, with some types lasting up to 10,000 milkings, depending on the material. Post-milking teat disinfection is effective for reducing contagious mastitis, while pre-milking dips help control environmental mastitis.*

Answer 66

Answer: **Epizootic bovine abortion** Explanation The correct answer is epizootic bovine abortion (EBA), also called foothill abortion. EBA is an important disease for beef producers in the foothill and mountainous regions of California, Northern Nevada and Southern Oregon. The lesions described in the question are consistent with this diagnosis. The etiologic agent of EBA is a bacteria, Pajaroellobacter abortibovis and the vector is a tick, Ornithodoros coriaceus. Tritrichomona foetus is involved with early embryonic death. Brucellosis abortions are rare since it has been almost completely eradicated from the U.S. Lesions include autolysis, placentitis, and bronchopneumonia. Infectious Bovine Rhinotracheitis (IBR) causes rapid fetal death; therefore, there is very little time for fetal response. Lesions you are likely to see include autolysis and focal necrosis of the organs.

Answer 67

Answer: **70% Normal** Explanation The correct answer is 70% normal. To be a satisfactory potential breeder, a bull must meet certain requirements including a normal physical exam, adequate scrotal circumference, sperm motility of at least 30% motile, and sperm morphology of at least 70% normal.

Answer 68

Answer: **Cull** Explanation The correct answer is cull. Unfortunately, there is very poor response to treatment and since this is a very contagious organism, it is best to cull. Other types of mastitis, such as Strep ag or coliform mastitis, may respond well to frequent milking, anti-inflammatories, and antibiotics.

Answer 69

Answer: **The heifer is intersex, infertile with masculinized behavior, non-functioning ovaries, and is genetically chimeric (XX/XY); the bull is phenotypically normal** Explanation Freemartinism is the normal result of mixed-sex twins in cattle. This occurs due to shared circulation of chorionic blood vessels in utero. This allows antimullerian duct hormone and testosterone from the male fetus to inhibit development of the female tract resulting in a short vagina that ends blindly without communication to the uterus. The heifer also frequently shows masculinized behavior. Cytogenetic examination of freemartins reveals both XX and XY chromosome patterns. Interestingly, although some bulls born as mixed-sex twins show the presence of XX cells, they have normal conformation and external genitalia and are fertile.

Answer 70

Answer: **Hypoderma bovis** Explanation The correct answer is Hypoderma bovis. H bovis is also known as the cattle grub, heel fly, or warble fly. The life cycle starts with the female attaching up to 500 eggs to the hairs around the hocks and lower portions of the cow. First-stage larvae will hatch in just a few days and burrow into the skin. At this point, they migrate towards the epidural fat in the spinal canal (H bovis) or via the esophagus (H lineatum). After several months, they become L2s and migrate to the subcutaneous tissues of the back where they will reach puberty, molt once more, and become L3s. Once they are L3s, swellings on the cows' backs can be felt. After 5-11 weeks, the L3s mature and burst through the skin, dropping on the ground where they will become adults in another 1-3 months. Cochliomyia hominivorax (aka screwworm) lays its eggs on skin wounds. The developing maggots feed on the flesh and can lead to multiple infestations from additional screwworms and other flies. Ornithodoros coriaceus (aka Pajahuello tick) is a soft tick that feeds on many different mammals and birds. This tick has become somewhat famous because it appears to transmit epizootic bovine abortion. Sarcoptes scabiei (aka scabies mange mite) causes mechanical and chemical irritation and intense pruritus, leading to loss of milk production and damage of hides due to scratching. Although this is a possible answer, the economic impact of Sarcoptes scabies is not as worrisome as with Hypoderma bovis.

Answer 71

Answer: **Bovine viral diarrhea (BVD)** Explanation BVD typically causes clinical illness in young susceptible animals exposed and stressed through transport or crowding and can result in oral ulcerations. ***PowerPage: Bovine Viral Diarrhea ***PowerLecture: Bovine Viral Diarrhea

Answer 72

Answer: **Vena caval thrombosis and metastatic pneumonia** Explanation By chance a liver abscess in a few animals that develop rumen acidosis may form near the posterior vena cava and cause infected thrombi to break off and move down pulmonary arteries into the lung until they lodge and form an abscess. Pulmonary embolic abscesses then create tracts from affected arteries to an airway, which results in pulmonary bleeding. This condition is extremely difficult to treat successfully and animals usually die within months of a massive bleed.

Answer 73

Answer: **Left displaced abomasum** Explanation The gas-filled abomasum has moved from its normal position near the ventral midline to the left of the rumen, where it is trapped (see image). As gas bubbles in and out, it sounds like the end of a toilet flush. When percussed and auscultated, the changing gas pressures yield a variable high-pitched ping. ***PowerLecture: Left Displaced Abomasum

Answer 74

Answer: **Macerated fetus** Explanation The correct answer is macerated fetus. The key to making this diagnosis is in feeling the crepitus, which is caused by bacterial degradation of the fetus. A mummified fetus is a sterile fetus in which all fluids are resorbed, leaving a firm tarry mass. With pyometra, the uterus will be distended with pus. Pyometras are usually seen post-partum. If you see one post-coital, consider Tritrichomonas foetus.

Answer 75

Answer: **Ivermectin** Explanation The correct answer is ivermectin. Albendazole and levamisole are used to treat worms. Ivermectin is more effective than pyrethrin.

Answer 76

Answer: **Meningitis** Explanation The correct answer is meningitis. This conclusion can be made by examining the CSF. An elevated CSF protein and CSF neutrophilia indicates a bacterial infection. Listeriosis tends to be associated with monocytosis of the CSF. The clinical signs and blood work are non-specific, and only the CSF results allow good differentiation between the other answer choices. With polioencephalomalacia the CSF changes in WBC count and protein will be much lower (5-50 WBCs/uL and protein slightly greater than 50mg/dl). Salt poisoning will not change the CSF protein and WBC count by much either.

Answer 77

Answer: **Streptococcus agalactiae** Explanation The correct answer is Streptococcus agalactiae. This organism usually causes subclinical mastitis, but sometimes you may see high somatic cell counts and clinical signs with this organism. Perform a CAMP reaction to diagnose this organism. That is when you plate S. aureus and S. agalactiae and you see them act together to lyse red blood cells. This creates a clearing on your culture plate.

Answer 78

Answer: **28 days** Explanation The correct answer is 28 days. Veterinarians can determine the fetal sex at approximately 58-90 days of gestation.

Answer 79

Answer: **PGF2-alpha will lyse her corpus luteum, increase uterine motility, evacuate her uterus, and bring her into estrus** Explanation PGF2-alpha has many effects, but chief among them is its luteolytic action. Lysis of the corpus luteum will immediately reduce circulating progesterone levels, allow the final development of an ovarian follicle, and bring the cow into estrus, which is accompanied by increased uterine motility, and in this case, drainage. PGF2-alpha will not likely stimulate the cow's appetite and would not do so by a direct therapeutic effect. PGF2-alpha will not decrease uterine contractility. PGF2-alpha will probably increase uterine contractility, both directly (utero-tonic effects) and indirectly, through the rise of estrogen that follows PGF2-alpha-induced luteolysis. PGF2-alpha is an inflammatory mediator. It will NOT directly suppress uterine inflammation. This cow needs an effective immune/inflammatory response to "clean up" her uterus. Anti-inflammatory therapy is not indicated. PGF2-alpha will NOT cause the maturation and ovulation of multiple follicles (i.e., superovulation). That is achieved by an altogether different class of hormones, the gonadotropins.

Answer 80

Answer: ** 2-5 years of age** Explanation The correct answer is 2-5 years of age, although younger and older animals can develop Johne's disease. Mycobacterium avium ssp paratuberculosis is the causative agent of Johne's disease in cattle. It causes wasting, diarrhea, and decreased production. The disease is economically devastating. There is no recommended treatment for the disease. Animals testing positive should be culled. ***PowerLecture: Paratuberculosis - Johne's Disease

Answer 81

Answer: **Repleace the liner every 25 milkings** Explanation The incorrect answer is to replace the liner after 25 milkings. This is the best answer because the liner will last for at least 500 milkings. There are three types of liners: synthetic rubber, natural rubber, and silicone. These are designed to last anywhere between 500 and 10,000 milkings. Post-milking teat disinfection is probably the most effective way of reducing the rate of contagious mastitis. Pre-milking dip will help control environmental mastitis.

Answer 82

Answer: **Tachycardia** Explanation The correct answer is tachycardia. Calcium administration may cause all the other abnormalities if you give too much too fast. You may also see a sinus node arrest. Calcium administration will cause the heart to beat more slowly and more strongly.

Answer 83

Answer: **Remove manually** Explanation The correct answer is to remove them manually. After removal it is recommended to treat with 10% levamisole drops. This is actually a photo of thelazia in a canine, but the appearance is very similar in cattle. The eye-worm can also be treated with ivermectin.

Answer 84

Answer: **Ceftiofur sodium** Explanation The correct answer is ceftiofur sodium. Ceftiofur or Naxcel used as labelled has a 4 day withdrawal time in meat. It has zero withdrawal time for milk. Chloramphenicol use is not allowed in food animals. Oxytetracline (LA200) has a 28 day meat withdrawal time. Sulfadimethoxine has a meat withdrawal time of 7 days. Penicillin G has a meat withdrawal time of 10 days.

Answer 85

Answer: **Send stool to diagnostic lab for 0157:7 specific fecal culture from all cattle.** Explanation E. coli 0157:H7 is an enterohemorrhagic strain of E. coli that produces "Shiga-like toxins" which cause illness in humans. The bacteria can exist in the intestines of healthy, normal cattle without causing signs or symptoms; therefore, there are no specific signs to look for when trying to identify suspects. A stool culture can detect the bacterium, but must be specifically requested. The sample is usually cultured on sorbitol-MacConkey (SMAC) agar. On SMAC agar, 0157 colonies appear clear due to their inability (unlike other E. coli serotypes) to ferment sorbitol. Non-sorbitol fermenting colonies are tested for the somatic 0157 antigen before being confirmed as E. coli 0157. Like all cultures, diagnosis is slow using this method, and swifter diagnosis is possible using PCR techniques. A PCR to detect Shiga-like toxin specific to 0157-H7 would be an equally good choice. You would pick culture or PCR based on speed and cost. In humans, common signs of infection are severe, acute hemorrhagic diarrhea and abdominal cramps, usually without fever. In most cases, the illness resolves in 5 to 10 days.

Answer 86

Answer: **Less than 1 year of age** Explanation The correct answer is nervous coccidiosis is a disease of cattle less than one year of age. This disease is caused by an enteric infection of Eimeria spp. It is thought that the coccidian produces a neurotoxin which results in the neurologic form of the disease.

Answer 87

In performing ocular ablation (removal) to treat severe cancer eye in a commercial beef cow, **which of the following is the most appropriate anesthesia to use in the field?** - General anesthesia using fluothane intubation following intramuscular xylazine - A five point orbital block using lidocaine - General anesthesia using sodium pentathol (barbiturate) - Sedation using xylazine and restraint in a squeeze chute - Topical anesthesia using proparacaine or tetracaine Answer: **A five point orbital block using lidocaine** Explanation Squamous cell carcinoma is by far the most common ocular tumor in cattle and is referred to as "cancer eye". Treatment can vary from resection of part of an eyelid to complete enucleation including the eyelids. Recurrence is common, as spread to the lymph node can occur if not caught early on. The cow should be restrained in a squeeze chute and the head tied to one side so that the abnormal eye is accessible. The area should be closely clipped or shaved and disinfected, then generous amounts (10 ml per site, 50 ml total) of local anesthetic are injected using a 19 ga 2.5 inch (6 cm) needle. The 5 injection sites include the medial canthus, and then twice through each lid so that the tissues around the globe are flooded with local. Alternatively the Peterson 's orbital nerve block (another local block) can be utilized.

Answer 88

Answer: **Sarcoptes scabei** Explanation The correct answer is Sarcoptes scabiei. Flies are the main vector of M. bovis, a.k.a. pink eye. Stomoxys calcitrans is the stable fly; Haematobia irritans is the horn fly; Musca autumnalis is the face fly. The face fly is one of the most commonly implicated vectors of all the flies. Sarcoptes scabiei is a reportable mite which induces severe pruritus and, as a result, may be economically devastating, but it is not involved in Moraxella transmission. ***PowerPage: Infectious Bovine Keratoconjunctivitis (Pinkeye)

Answer 89

Answer: **Change feed and treat** Explanation The correct answer is to change feed and begin treatment of the animals affected with woody tongue, as the response is often good. Sodium iodide and antibiotics are effective. Given the presentation and clinical signs, these animals have probably begun to ingest very rough and stemmed (scabrous) feed items that have injured their mouths. Upon injury, the normal inhabitant Actinobacillus lignieresii invades the soft tissues and causes the characteristic woody tongue granulomatous inflammation. These animals don't have rabies, and there is no need to cull them. Change feed before additional animals are affected. Do not use aminoglycosides as they have an extremely long withdrawal period.

Answer 90

Answer: **Expose heifers to endemic areas before breeding age** Explanation This is the typical presentation for epizootic bovine abortion (EBA), also known as foothill abortion. The agent causing foothill abortion remains a subject of some investigation but a 2005 molecular study identified a novel deltaproteobacterium as being present in the Ornithodoros coriaceus tick vector and in DNA from fetal thymuses. With EBA, cows usually do not experience abortions again in later pregnancies and exposure to endemic areas before breeding age can also prevent abortions. Other control options may include control of the tick vector or prophylactic antibiotic use. You can lower your index of suspicion for bovine herpesvirus (Infectious bovine rhinotracheitis virus) because there is no respiratory disease seen in this case; abortions from herpesvirus occur throughout pregnancy and fetuses are typically autolyzed with foci of necrosis in the liver or no gross lesions. Ponderosa pine needle abortions occur in the last trimester but cows are often moribund after delivery and hemorrhage. There are usually no specific fetal lesions.

Answer 91

Answer: **Approximately 2.5 years** Explanation The correct answer is approximately 2.5 years of age. A good rule of thumb is that the permanent incisors are in wear at 1.5, 2.5, 3.5 and 4.5 years of age (permanent incisors 1, 2, 3, and 4 respectively).

Answer 92

Answer: **Vaccination of all calves against BRSV** Explanation Until the calves have time to develop immunity, new animals should be raised apart from and isolated from the current group of calves where the virus is circulating. Treatment of individual calves affected by BRSV may include antimicrobial drugs and NSAIDs; some veterinarians advocate the use of corticosteroids if pulmonary edema is severe.

Answer 93

Answer: **Pneumothorax** Explanation The correct answer is pneumothorax. Since there is free air in the chest, the lung has lost its vacuum and is collapsed. The free air moves dorsally and you are unable to hear any lung sounds. Fibrinous pleuropneumonia will have lung sounds associated with it. Aspiration pneumonia is usually cranioventral in location. Pulmonary contusion is a differential, but given the location, a pneumothorax is more likely.

Answer 94

Answer: ** A 5-month old calf which was persistently infected as a fetus with a non cytopathic (nonCPE) biotype of BVD virus is superinfected with a cytopathic (CPE) biotype of BVD due to rearranging of the parent non-CPE viral RNA.** Explanation This is the correct answer because it describes the current understanding of the pathogenesis of both mucosal disease and chronic BVD. A 5-month old calf is infected with CPE biotype of BVD virus and then superinfected with a nonCPE biotype of BVD virus is incorrect because it does not say that there was persistent fetal infection; also, the order of the superinfection is the reverse of what causes mucosal disease or chronic BVD. A 5-month old calf which was persistently infected with the nonCE biotype of BVD virus as a fetus forms antigen-antibody complexes which cause a fatal immune-mediated disorder is incorrect because this is not the mechanism by which mucosal disease or chronic BVD occur. All other answer choices are incorrect because they each describe one of the acute clinical syndromes from primary infection, rather than either mucosal disease or chronic BVD. **PowerPage: Bovine Viral Diarrhea

Answer 95

Answer: **Surgical removal using sedation and local anesthesia** Explanation The medical term for a corn is interdigital hyperplasia. Corns are thought to result from stretching of the insertions of the distal interphalangeal ligament in heavy beef breeds. In dairy breeds, corns can occur when cows are continuously standing in slurry, or have some other chronic source of irritation such as interdigital dermatitis. Corns are best treated by surgical removal of the mass, being careful to avoid the interdigital fat pad. The area is then bandaged, and the claws can be temporarily wired together if necessary. Wiring the claws is often not necessary if the surgery is only skin deep.

Answer 96

Answer: **The cow appears to have vagal indigestion of undetermined cause and is unlikely to respond to medical management** Explanation This cow likely has vagal indigestion based on the chronicity and clinical appearance. Frothy bloat is typically much more acute. Due to the severity and chronicity of this cow's signs, its prognosis should be considered poor even without determination of the specific underlying cause. Most cases of vagal indigestion require surgery to identify the underlying cause and medical management alone is usually ineffective.

Answer 97

Answer: **Magnesium oxide** Explanation The correct answer is magnesium oxide, which becomes Mg OH in the rumen. You may also use magnesium hydroxide or magnesium carbonate. Vinegar will cause acidification of the rumen and is therefore a poor choice. Propylene glycol and bismuth subsalicylate will not affect rumen pH significantly.

Answer 98

Answer: **Rumen** Explanation The correct answer is rumen. The location extending up to the hip and the monotone "boink" (not ping) are indicative of the rumen. A cow with LDA would have a variable-pitched ping heard to only just in back of the last rib (not to the hip). It is variable because the rumen is usually still contracting medial to the displaced abomasum, and the changing gas pressures result in a pitch that changes during percussion and auscultation.

Answer 99

Answer: **3.5 y** Explanation The correct answer is approximately 3.5 years of age. A good rule of thumb is that the permanent incisors are fully erupted and in wear at 1.5, 2.5, 3.5 and 4.5 years of age (permanent incisors 11, 12, 13 and 14 respectively). The first permanent incisor erupts at 18 to 24 months, the second at 24 to 30 months, the third at 33 to 36 months, and the fourth erupts at 42 and 48 months. This means that the rough rule of thumb is a bit off for 11 in some animals, but it does help to remember these approximate times. There is some individual and some breed variability. After eruption, each tooth takes about 6 months before it is in wear.

Answer 100

Answer: **Left displaced abomasum** Explanation The gas-filled abomasum has moved from its normal position near the ventral midline to the left of the rumen, where it is trapped (see image). As gas bubbles in and out, it sounds like the end of a toilet flush. When percussed and auscultated, the changing gas pressures yield a variable high-pitched ping. ***PowerLecture: Left Displaced Abomasum

Answer 101

Answer: **IV fluids with added sodium bicarbonate** Explanation This calf is typical of those suffering from nonspecific calf diarrhea, most often associated with enteropathogenic E coli, rotavirus, or cryptosporidium. The calf develops hypovolemia and metabolic acidosis and requires sodium-containing IV fluids which contain additional alkali such as sodium bicarbonate. One can assess that the calf is severely acidotic given that it is lethargic and unable to stand. While oral fluids may also be useful, at this stage, the calf will require IV fluids. ***PowerLecture: Calf Diarrhea Part 2

Answer 102

Answer: **Free gas bloat, failure to eructate** Explanation This is sometimes called Type 1 vagal indigestion, or free gas bloat. It is frequently associated with swollen mediastinal lymph nodes caused by pneumonia. The signals to or from dorsal rumen receptors, which detect gas pressure and open the cardia, are compromised such that eructation does not occur normally and free gas bloat occurs. This in turn causes the calf to feel full and it eats poorly and loses weight. One needs to treat the pneumonia and perhaps create a temporary rumen fistula to allow the escape of gas until eructation returns to normal. ***PowerLecture: Vagal Indigestion **Vagal indigestion**, also known as Hoflund syndrome, is a chronic condition in ruminants characterized by impaired gastrointestinal motility leading to abdominal distension and altered digestion. Presentation and Classification: Vagal indigestion results from functional or mechanical disruptions affecting the forestomach’s motility, often due to vagal nerve damage. Traditionally, it is classified into two primary types: 1. Proximal Functional Stenosis (Type I): Impaired passage of ingesta from the reticulorumen to the omasum and abomasum, leading to rumen distension. 2. Distal Functional Stenosis (Type II): Impaired abomasal emptying, resulting in abomasal distension and potential reflux into the omasum and reticulorumen. Clinical Signs Common clinical manifestations include: • Progressive abdominal distension, often presenting a “papple-shaped” contour (apple-shaped on the left, pear-shaped on the right). • Decreased appetite and weight loss. • Reduced fecal output, sometimes with larger particle sizes. • Altered rumen motility, ranging from hypomotility to hypermotility. • Bradycardia, with heart rates less than 60 beats per minute. • Signs of dehydration and poor coat condition. Diagnosis A comprehensive diagnostic approach includes: • Clinical Evaluation: Observation of abdominal distension and auscultation for rumen motility. • Atropine Response Test: Subcutaneous administration of 40 mg atropine sulfate; an increase in heart rate by more than 16% suggests vagal nerve involvement. • Rumen Fluid Analysis: Measurement of rumen chloride concentration aids in differentiating between proximal and distal stenosis. Elevated rumen chloride levels indicate distal stenosis. • Ultrasonography: Identification of adhesions, abscesses, or other lesions affecting motility. • Exploratory Laparotomy: Direct visualization to confirm mechanical obstructions or adhesions. Treatment Management strategies focus on addressing the underlying cause: • Medical Therapy: Correction of electrolyte imbalances, particularly hypochloremia and hypokalemia, through intravenous fluids. • Prokinetic Agents: Administration of erythromycin (10 mg/kg IM) to enhance abomasal motility, especially post-surgically. • Surgical Intervention: Indicated for cases involving mechanical obstructions, adhesions, or abscesses unresponsive to medical management. • Supportive Care: Ensuring adequate nutrition and hydration, and monitoring for complications such as peritonitis. Prognosis The prognosis varies based on the underlying cause and response to treatment. Cases without identifiable etiologies or those with permanent vagal nerve damage often have a poor prognosis. Early detection and intervention are crucial for improving outcomes. Further Reading For an in-depth understanding, refer to the following resources: • Merck Veterinary Manual: [Chronic Indigestion Syndrome in Ruminants](https://www.merckvetmanual.com/digestive-system/diseases-of-the-ruminant-forestomach/chronic-indigestion-syndrome-in-ruminants?utm_source=chatgpt.com) • dvm360: [Physical Examination of Cattle: Parts I and II](https://www.dvm360.com/view/physical-examination-cattle-parts-i-and-ii-proceedings?utm_source=chatgpt.com) • Merck Veterinary Manual: [Peritonitis in Animals](https://www.merckvetmanual.com/digestive-system/peritonitis/peritonitis-in-animals?utm_source=chatgpt.com)

Answer 103

Answer: **Grave (‹10% chance of survival and recovery)** Explanation This calf has an abomasal perforation and acute septic peritonitis based on the description. The prognosis is grave, even with prompt veterinary attention. The calf's signs of dehydration, weakness, and expiratory grunt are additional poor prognostic indicators. Very few animals recover from diffuse peritonitis and those that do will have massive abdominal adhesions. Acute abomasal perforation through a single 1-2 cm ulcer occurs sporadically in young (2-4 month old) beef calves and the cause is unknown.

Answer 104

Answer: **Surgically resect the intussusception** Explanation Hopefully you will be able to recognize that the "mass" visualized in this image is an intussusception. After removal, an end-to-end anastomosis of the intestine is performed, and the cow is aggressively treated with antimicrobial drugs and IV fluids with a good content of chloride, such as saline, since these animals are usually suffering from hypochloremic hypokalemic metabolic alkalosis. ***PowerLecture: Colic

Answer 105

Answer: **The cattle are suffering from type ll ostertagiasis; treat with ivermectin** Explanation Outbreaks in autumn into winter in climates like California with hot dry summers and cool wet fall and winter are associated with type Il ostertagiasis in the cool season. In this manifestation of disease, fecal egg counts are low and there are thousands of inhibited early fourth-stage larvae ready to exit the abomasal glands. Once a full blown type Il infection occurs, many larvae emerge, causing dysfunction of the abomasum and possibly leading to severe albumin loss, diarrhea, and even death. In contrast, type I ostertagiasis in California climates occurs in winter and spring following rapid infection with large numbers of L3 larvae from heavily contaminated pastures (or on irrigated summer pasture). Egg counts in this scenario tend to be much higher and clinical disease is most common in younger animals after weaning. However, in older animals, after invading the abomasal mucosa, many of the larvae have inhibited or delayed development at the L4 stage and wait for favorable climate conditions to emerge and cause type Il disease. In climates with rainy summers and freezing winters the emergence will often be in spring. So climate affects the time that Type Il is seen. As for treatment, benzimadazoles (i.e. fenbendazole) and ivermectin are generally more effective than levamisole but all are treatment options. Answer: **The cattle are suffering from type ll ostertagiasis; treat with ivermectin** Explanation Outbreaks in autumn into winter in climates like California with hot dry summers and cool wet fall and winter are associated with type Il ostertagiasis in the cool season. In this manifestation of disease, fecal egg counts are low and there are thousands of inhibited early fourth-stage larvae ready to exit the abomasal glands. Once a full blown type Il infection occurs, many larvae emerge, causing dysfunction of the abomasum and possibly leading to severe albumin loss, diarrhea, and even death. In contrast, type I ostertagiasis in California climates occurs in winter and spring following rapid infection with large numbers of L3 larvae from heavily contaminated pastures (or on irrigated summer pasture). Egg counts in this scenario tend to be much higher and clinical disease is most common in younger animals after weaning. However, in older animals, after invading the abomasal mucosa, many of the larvae have inhibited or delayed development at the L4 stage and wait for favorable climate conditions to emerge and cause type Il disease. In climates with rainy summers and freezing winters the emergence will often be in spring. So climate affects the time that Type Il is seen. As for treatment, benzimadazoles (i.e. fenbendazole) and ivermectin are generally more effective than levamisole but all are treatment options.

Answer 106

Answer: **Malignant catarrhal fever (MCF)** Explanation MCF is caused by a herpes virus carried by sheep in North America and called ovine herpesvirus type 2. The virus affects lymphocytes and allows the animal's own killer cells to attack blood vessels, resulting in arteritis. Arteritis results in multisystemic signs, high fever, and enlarged lymph nodes. The acute severe form such as described here is usually fatal. While a small number of cattle with BVD may develop corneal opacity, they do not usually have the enlarged lymph nodes and the combination of other signs seen with MCF. ***PowerLecture: Malignant Catarrhal Fever - MCF

Answer 107

Answer: **Valvular endocarditis** Explanation Bacteria can lodge on heart valves and collect platelets and do damage to valves, causing murmurs and dysfunction and in some cases heart failure. The bacteria usually enter via a septic site such as a hoof abscess. Valuable cows should be treated with penicillin or ceftiofur for several days if they develop hoof abscesses or similar problem.

Answer 108

Answer: **Vitamin A deficiency** Explanation The correct answer is vitamin A deficiency. The clinical signs are very similar in these two other neurologic diseases. However, pupillary light reflex will stay intact with salt poisoning, and lead poisoning. PLRs disappear with vitamin A deficiency as a result of retinal degeneration and constriction of CN Il at the level of the optic foraminae. Blood work will usually be unremarkable. CS changes in Vit A deficiency include a mononuclear cell pleocytosis of 40-50 cell/dl and increased protein of approximately 140mg/dl. It is more common for unsupplemented feedlot animals to be deficient because they do not have access to vitamin A rich, green, succulent, plants. The vitamin A requirement for most species is between 40-80 IU/kg of body weight daily. Vit C deficiency will not cause CNS signs of this type.

Answer 109

Answer: **A recent metritis/uterine infection** Explanation The correct answer is a recent uterine infection. Cows presenting with clinical signs suggestive of tetanus infection often have had a recent uterine infection. Cattle tend to develop tetanus less commonly than horses, sheep, or goats, as they are less sensitive to the toxin. Calving or surgical castration are common in the history. Tetanus may develop from hoof wounds, as occurs in horses, but this is rare in cattle. The tetanus toxin moves retrograde up the peripheral neuron into the spinal cord, where it prevents release of inhibitory neurotransmitters such as GABA. This inactivation of inhibitory neurotransmission causes spastic paralysis. It is possible to develop tetanus from hoof wounds, as is common in horses, but this is very uncommon in cattle.

Answer 110

Answer: **feeding program*** Explanation The clinical description and pathologic findings are consistent with rumen acidosis, likely secondary to dysfunction of the esophageal groove (also known as reticular groove). To review normal physiology, the esophageal groove (also known as reticular groove) is a specialized part of the ruminant stomach that closes in response to drinking milk, guiding it directly to the abomasum. When dysfunctional, milk goes to the rumen where it is fermented by rumen microbes and converted to volatile fatty acids and lactic acid. The resulting rumen acidosis leads to the clinical signs described in this case. For this reason, this phenomenon is sometimes referred to as rumen drinking. There are a number of predisposing factors to this problem. The major contributors are stress, irregular feeding, feeding poor quality milk replacer, feeding milk at too cold of a temperature (should be body temperature), tube feeding, diarrhea, and bucket drinking. Of the options in this question, the best choice is to review the feeding program because it involves so many of the predisposing factors.

Answer 111

Answer: **Lipids** Explanation A typical TPN mixture for a calf this size would be 1L of 10% amino acids, 1L of 50% glucose and 500 ml of 10% lipids per day.

Answer 112

Answer: **Vitamin E and selenium deficiency** Explanation The correct answer is vitamin E and selenium deficiency (white muscle disease). The clinical signs are somewhat compatible with the other answers; however the necropsy results are diagnostic for white muscle disease. There is both a cardiac form, in which animals die acutely, and a skeletal muscle form, in which animals don't die acutely but show clinical signs. In this particular question, the ranch was suffering from both forms. Remember that oleander and gossypol are both cardiotoxic and can cause acute death. Given the necropsy findings, clostridial myositis would be unlikely. Selenium is essential for glutathione peroxidase, deiodinase, and selenoprotein-P to work. Glutathione peroxidase breaks hydrogen peroxide and lipoperoxide into water or harmless alcohols.

Answer 113

Answer: **Failure of passive transfer (FPT) and sepsis, with hypopyon** Explanation The history of a neonate with these signs and an elevated temperature, scleral injection and hypopyon are indicative of bacterial sepsis, a result of FPT.

Answer 114

Answer: **Yew** Explanation Both Japanese yew (Taxus cuspidata) and English yew (T. baccata) contain alkaloids called taxines that are highly toxic and depress myocardial conduction by blocking sodium movement through membranes. Collapse and sudden death are commonly seen when this plant is ingested, often when clippings are consumed by livestock. Oleander causes similar clinical scenarios.

Answer 115

Answer: **Streptococcus agalactiae** Explanation The correct answer is Streptococcus agalactiae. This organism usually causes subclinical mastitis, but sometimes you may see high somatic cell counts and clinical signs with this organism. Perform a CAMP reaction to diagnose this organism. That is when you plate S. aureus and S. agalactiae and you see them act together to lyse red blood cells. This creates a clearing on your culture plate.

Answer 116

Answer: **Intravenous sodium iodide** Explanation The correct answer is intravenous iodine. It is commercially available as a 20% solution at a dose of 15 ml/100 Ibs (66 mg/Kg). The clinical signs are suggestive of lumpy jaw, which is caused by Actinomyces bovis. The prognosis is poor, so most animals should be culled. Penicillins are reportedly successful at arresting the lesion in very early cases. However, there may be a better chance with intravenous 20% sodium iodide. That being said, due to concerns that iodide may cause abortion and because of food safety concerns, the label warns not to use sodium iodide in pregnant or lactating cattle. Ceftofur may not be used in this extra label fashion.

Answer 117

Answer: **Treat all animals with tetracycline to eliminate carriers and regularly vaccinate all cattle against this serovar** Explanation Since Hardjo-Bovis is carried by cattle, he needs to both treat and vaccinate. Vaccination can prevent new carriers, but will not eliminate existing carriers. To be cost effective, he may need to mass treat dry cows and young stock using long acting tetracycline. Swine (and opossums, skunks and raccoons) are carriers of Pomona, dogs of Canicola, rats of Icterohemorrhagiae, swine, mice and horses of Bratislava, and raccoons, muskrats and squirrels of Grippotyphosa.

Answer 118

Answer: ** Wildlife (deer)** Explanation In the USA, the most common reservoir infecting cattle are white tailed deer; badgers in Great Britain; brushtail possums in New Zealand. These reservoirs make control and eradication very difficult.

Answer 119

Answer: **Treatment is unlikely to be successful and the cow should be culled** Explanation This is a case of Actinomyces bovis or "lumpy jaw". The keys to the diagnosis are the firm mass that is immobile over the mandible. The presence of "sulfur granules" in the discharge is also a characteristic finding with this disease. Unfortunately, simply making the diagnosis is not sufficient to answer this question correctly. All of the answer choices are potential treatments for lumpy jaw but this represents a moderate to severe case which is unlikely to respond to treatment due to difficulty in achieving the necessary antibiotic concentration over a sustained period. Therefore, the best answer choice in this case is to cull the cow.

Answer 120

Answer: **Hypomagnesemia** Explanation Hypomagnesemic tetany (grass tetany) can cause all of these signs. It usually occurs in cold or cool weather in pastured lactating beef or dairy cows. Lush pastures that are high in potassium and nitrogen and low in magnesium and sodium are most often involved. Hypocalcemia may cause similar signs in periparturient cows (milk fever).

Answer 121

Answer: **Infectious bovine rhinotracheitis** Explanation The correct answer is infectious bovine rhinotracheitis. There are three subtypes of infectious bovine rhinotracheitis identified. BHV-1.1 (Bovine herpes virus) is responsible for respiratory infections. BHV-1.2 may cause genital infections and respiratory disease. BHV-1.3 (reclassified recently and now called BHV 5) has been known to cause neurologic infections. Since most people are not aware of the reclassification, this aspect of the issue is unlikely to be questioned on a board examination. All of the other listed answer choices can cause the lesion described in the question.

Answer 122

Answer: **Preconditioning all calves prior to entry into the feedlot** Explanation Preconditioning involves being sure that calves are weaned several weeks before entering the feedlot, vaccinated against infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD), Parainfluenza-3 (PI3), and Clostridial diseases. They should be dewormed, and dehorned and castrated if not already done. Ideally, the calves should also have learned to eat from a bunk and drink from a trough before entering the feedlot. Then, when the calves are mixed with calves from other ranches, they are less likely to succumb to respiratory disorders.

Answer 123

Answer: **Ruptured urethra** Explanation In the bovine, urolithiasis often results in rupture of the urethra. Urine then leaks into all the ventral tissues and causes this massive ventral edema, which progresses to necrosis and sometimes to gangrene. ***PowerLecture: Urolithiasis In Ruminants

Answer 124

Answer: **Perineal urethrostomy** Explanation An exit for the urine is made surgically in the perineal area. This is a salvage procedure to get the animal to slaughter in one to 3 months when the tissue damage from any extravasated urine resolves sufficiently in the event that the urethral obstruction was more distal. Treatment with sodium containing intravenous fluids would be ineffective as long as there is active leakage of urine into the abdomen. A surgical correction or diversion is necessary to stabilize this patient. Since this is a feedlot steer the most cost effective management decision is to perform a perineal urethrostomy proximal to the point of obstruction. This repair assumes that the ruptured bladder will be able to heal on its own. ***PowerLecture: Urolithiasis In Ruminants

Answer 125

Answer: **Listeria monocytogenes** Explanation Listeria monocytogenes is the most common CNS infection in adult ruminants. Infection is often associated with feeding of silage. It causes microabscesses in the brain resulting most commonly in unilateral cranial nerve signs such as facial nerve paralysis, vestibular signs (circling), head tilt, and dysphagia. CN V-XII may be involved. Head pressing may be seen in some cases. It is also a cause of abortions. Treatment is with tetracyclines or high levels of penicillin. Mycoplasma bovis in young calves can affect some animals with otitis interna, so the calf shows (uni or bilateral) facial paralysis, ear droop, and vestibular signs such as head tilt, nystagmus, and ataxia. There may be purulent discharge from the aural canal. M bovis can also cause pneumonia, polyarthritis and tenosynovitis. This condition can be difficult to treat and result in many animals with chronic illness. Histophilus somni can commonly be a cause of respiratory disease and septicemia, as well as TEME (thromboembolic meningoencephalitis) or otitis media /interna in young feedlot animals where they exhibit head tilt, nystagmus, circling and stumbling. They may also develop ipsilateral facial paralysis. So in this case the main differential is the age of the animal and the fact that this is often a feedlot animal, plus H somni tends to be a more fulminant systemic disorder. ***PowerLecture: Central Nervous System

Answer 126

Answer: **Chokecherry** Explanation The correct answer is chokecherry. This is a cyanide-containing plant and can cause dyspnea, staggering, and death. Bright red mucous membranes are commonly seen due to the result of the cyanide interfering with the electron transport chain (binds to cytochrome oxidase); hemoglobin is unable to release oxygen. For some reason, the Gl tract has a bitter almond smell on necropsy. All other answer choices are pyrrolizidine alkaloid plants.

Answer 127

Answer: **Vitamin D deficiency** Explanation The correct answer is vitamin D deficiency. Vitamin D deficiency will manifest with bone abnormalities (rickets). Vitamin A deficiency may produce an encephalopathy in which convulsions and blindness are common clinical signs. Copper deficiency may result in demyelination and pathologic fractures of the vertebrae. Thiamine deficiency produces polioencephalomalacia.

Answer 128

Answer: **Hyponatremia, hypochloremia, hyperphosphatemia** Explanation These are the electrolyte abnormalities that should be expected in cases of uroabdomen. There would also be azotemia (elevated urea nitrogen), and possibly hyperkalemia in the blood. ***PowerLecture: Urolithiasis In Ruminants

Answer 129

Answer: **Campylobacter fetus ssp venerealis** Explanation The correct answer is Campylobacter fetus ssp. venerealis, which is the main cause of bovine campylobacteriosis but is not shed in milk. This organism is an obligate parasite of the bovine genital tract and causes abortion. Infection usually results in temporary infertility or early embryonic death. A different Campylobacter, C jejuni, is an emerging milk zoonotic pathogen. M avium ssp paratuberculosis is believed by some individuals to be a possible human pathogen, perhaps responsible for some (but not all) cases of Crohn's disease. The majority of evidence would disagree with that position, but agree that it should not be present in milk for human consumption.

Answer 130

Answer: **Before purchase, test all heifer replacements for BVD virus using immunohistochemistry on a skin biopsy** Explanation BVD is brought into herds such as this via persistently infected animals that were congenitally infected with BVD virus. These animals shed virus and infect herd mates. Thus it is necessary to check all purchased animals to be sure they are BVD free. It would also be wise to also vaccinate all cattle on this dairy with killed BVD vaccine just to ensure that if BVD did appear, it would be less likely to cause a major problem. Initial vaccination requires two injections, followed by a yearly booster. Vaccination alone however, will not keep the herd BVD free if a BVD carrier heifer is brought

Answer 131

Answer: **Apply wooden hoof block to left rear lateral claw** Explanation This is easy and inexpensive and gets the cow's weight off the sore medial claw so she will ambulate and eat relatively normally.

Answer 132

Answer: **High mountain disease** Explanation The key to this question is the altitude mentioned in the question and accompanying clinical signs. Also called brisket disease and high altitude disease, this condition can be fatal and is brought on by elevations above 6000 feet. Hypoxic vasoconstriction (worse in some lines of cattle) causes pulmonary hypertension, which leads to cor pulmonale, which is secondary cardiac disease including right heart enlargement and failure.

Answer 133

Answer: **Histophilus somni** Explanation The correct answer is Histophilus somni (old name was Hemophilus somnus). TEME affects the cerebellum and brain stem, but H. somni can cause other signs of systemic disease such as pneumonia, laryngeal disorders, joint infections, metritis, orchitis, and conjunctivitis. Initial infection in cattle (usually 4-12 months old) probably occurs through the respiratory tract. Many times respiratory signs are seen before neurologic signs develop. The disease gets its name because endothelial cells become infected and then degenerate and expose the subendothelial collagen thus triggering the clotting cascade and resulting in thrombi (but no emboli). Lesions seen include multifocal hemorrhages and infarctions in the brain stem, cerebral cortex, and spinal cord. CSF fluid will be xanthochromic and cloudy due to increased numbers of neutrophils. This disease can be difficult to distinguish from polioencephalomalacia except that TEME has high fever. ***PowerLecture: Central Nervous System

Answer 134

Answer: **Escherichia coli** Explanation The correct answer is Escherichia coli. This is an environmental contaminant and not a contagious organism. Pre-milking teat dips are useful for preventing such noncontagious diseases as E. coli, Enterococcus, and Streptococcus sp. other than S. agalactiae. Post-milking teat dips help prevent the spread of contagious pathogens such as Strep agalactiae from the skin into the streak canal and gland.

Answer 135

Answer: **Push forward on the vagina while rolling the cow clockwise** Explanation The correct answer is push forward on the vagina while rolling the cow clockwise, which may seem counter-intuitive. By stabilizing the uterus and rotating the cow around it, you can attempt to relieve the torsion.

Answer 136

Answer: **Blood transfusion with fresh whole blood** Explanation The thrombocytopenia is caused by BVD virus adhering to thrombocytes which are then removed by the reticuloendothelial (RE) system. Once the number gets this low, fatal hemorrhage is possible at any moment. Although not usual, this form of BVD has been described. The other forms of therapy may be needed as well. If the calf survives, you will also need to determine whether or not he remains persistently infected with BVD... if he does, he should not be retained.

Answer 137

Answer: **Escherichia coli** Explanation The correct answer is Escherichia coli. This is an environmental contaminant and not a contagious organism. Pre-milking teat dips are useful for preventing such noncontagious diseases as E. coli, Enterococcus, and Streptococcus sp. other than S. agalactiae. Post-milking teat dips help prevent the spread of contagious pathogens such as Strep agalactiae from the skin into the streak canal and gland.

Answer 138

Answer: **Genetic** Explanation The correct answer is genetic (autosomal-recessive). The condition is the result of a defect of the enzyme alpha-mannosidase and is seen in Murray gray, Simmental, Holstein, Galloway, and Angus cattle. The cleavage between N-acetyl glucosamine and mannose will not occur and the oligosaccharide will accumulate within the lysosomes of neurons, reticuloendothelial cells, and macrophages. The first sign at 1 month to 15 months of age will be a mild ataxia of the pelvic limbs after exercise. Other signs then develop, including hypermetria, aggressiveness, and intention head tremors. Most affected individuals will end up getting diarrhea and becoming recumbent and die within months after diagnosis.

Answer 139

Answer: **Treat all calves for lice** Explanation This is a blood sucking genus of louse, and can cause severe anemia. The anemic calves become thin and more susceptible to diseases like pneumonia. You can tell this is a louse and not a tick or a mite because lice are insects with 6 legs and ticks and mites are arachnids with 8 legs. The three genera of blood sucking cattle lice are Solenopotes, Linognathus, and Hematopinus.

Answer 140

Answer: **ELISA for BLV antibodies** Explanation The best answer to this question is ELISA for BLV antibodies. A biopsy is definitive if you can demonstrate antigen with immunohistochemistry, but many diagnostic labs do not have this capability, so this answer option was not included for this question. The ELISA for BLV only reveals that the cow has antibodies to BLV virus, but not that she has clinical lymphoma. However, multiple enlarged lymph nodes and a positive BLV antibody test are strongly suggestive of lymphoma. A negative ELISA test would rule out BLV and associated lymphoma. Aspiration of lymph nodes can lead to false positives, as many inflamed reactive nodes in cattle can have cells that look neoplastic. The AGID for BLV antibodies is less sensitive than ELISA. The WBC and lymphocyte count lacks sensitivity and specificity.

Answer 141

Answer: **Flush the wound and let it heal** Explanation The correct answer is flush the wound and let it heal. C. pseudotuberculosis manifests itself as sores and abscesses in cattle. They are most common on the lateral thorax, neck, flank, or head. It is thought that an injury can result in inoculation of the organism. Cows are relatively unaffected systemically, and the lesions will resolve on their own in 2-4 weeks. In sheep and goats the disease is called caseous lymphadenitis and the lesions seen can be external abscesses called "boils", which are spread by shearing in sheep, or internal abscesses that result in weight loss and emaciation. There is a vaccine against this condition in sheep.

Answer 142

Answer: **Bristle grass (Setaria lutescens) irritation** Explanation Yellow bristle grass contains sharp miniature barbs that stick into the mucosa of young cattle and horses and cause ulcers. Simple removal from the diet results in healing.

Answer 143

Answer: **Right side and intracranial** Explanation The correct answer is right side and intracranial. This is evident because the head tilt and cranial nerve deficits are usually on the side of the lesion and all of these are occurring on the same side in this situation. If you have to guess go with ipsilateral to the lesion. This is an intracranial problem since you have conscious proprioceptive deficits, head pressing, and depression.

Answer 144

Answer: **Silicate** Explanation Silicate stones are the result of high intakes of silica in mature range grasses, combined with other factors such as dehydration. Struvites (ammonium, magnesium, and phosphate) tend to be found in feedlot animals receiving large amounts of grain. Calcium carbonate stones are most common in sheep grazing pastures high in calcium and oxalates.

Answer 145

Answer: **Infectious bovine rhinotracheitis** Explanation The correct answer is infectious bovine rhinotracheitis. The key clinical sign to make this diagnosis is the white fibrinonecrotic plaques. None of the other answer choices cause white fibrinonecrotic plaques.

Answer 146

Answer: **Intussusception** Explanation The only choices likely to cause colic are intussusception, cecal dilation, and abomasal ulcer. Of those 3, only intussusception would cause scant, sticky, dark feces. The intussusception usually occurs in the jejunum or ileum, and results in a backed-up Gl tract. This causes chloride to be sequestered in the abomasum, as well as internally vomited into the rumen, resulting in hypochloremia, hypokalemia, and metabolic alkalosis. A PCV of 30% is normal for a cow, so a bleeding ulcer is unlikely; the HR of 100/min in this case is likely due to pain rather than anemia. ***PowerLecture: Colic

Answer 147

Answer: **There is no effect** Explanation The correct answer is that there is no effect when the cow is in anestrus. That is the problem with using PGF2-alpha to synchronize estrus cycles in cows. A mature corpus luteum is needed so that PGF2-alpha can lyse it; the cow goes back into estrus in about 2-5 days.

Answer 148

Answer: **IV calcium** Explanation This cow has the history and classic signs of hypocalcemia, also called milk fever. Skeletal, cardiac and smooth muscle weakness lead to the signs, and she is unable to maintain her body temperature in cold weather.

Answer 149

Answer: **This cow is infected with a coliform** Explanation The correct answer is this cow is infected with a coliform. This is a typical secretion and other clinical signs with coliform mastitis, although coliform mastitis can also present with mild clinical signs. Trueperella pyogenes mastitis is usually thick pus and the cow is not so ill. Staph aureus can also cause systemic signs of illness, or gangrenous mastitis when severe. It is usually found in a herd without a comprehensive mastitis prevention and control program. Mycoplasma bovis and a few other species can cause mastitis in cows, but M mycoides is mainly a problem of mastitis in does and systemic illness and arthritis in young goats.

Answer 150

Answer: **Atrial fibrillation** Explanation The correct answer is atrial fibrillation. This usually occurs as a result of digestive disturbances. It is associated with vagal tone, hypokalemia, hyperkalemia, and calcium therapy. You may be able to palpate a pulse deficit and/or pulsus alternans in these animals. On ECG, there will be no P waves because the sinoatrial node is not working. You will see random high frequency, low amplitude depolarizations called F waves. A QRS wave that occurs at irregular intervals will be present.

Answer 151

Answer: **Lupine alkaloids can be teratogenic in cattle** Explanation Different quinolizidine alkaloids in various species of lupine can cause either neurologic signs or teratogenesis. Sheep are often more affected with neurologic signs by acute toxicity to lupine, although cattle and horses can also be affected. Cattle experience fetal teratogenesis more often than sheep. Classic lesions are arthrogryposis (crooked calf) or cleft palate. Some laboratories can assay for lupine alkaloids in urine or serum, so these can be collected to help confirm the diagnosis in the sheep. Other plants with similar nicotinic-acting alkaloids include tobacco, Indian tobacco and tree tobacco, locoweeds, Scottish broom, mountain thermopsis, and poison hemlock. The best course of action is to move the animals to safer pastures. Pyrrolizidine alkaloids are liver toxins and are not noted in this pasture. Bone marrow suppression occurs in cattle that consume large amounts of bracken fern. Brown-colored blood is associated with nitrate toxicity, which is associated with other plants.

Answer 152

Answer: **Vagal indigestion** Explanation The most common cause of vagal indigestion is a metallic foreign body penetrating the reticulum (hardware disease). The local peritonitis leads to poor motility of the forestomachs, so that the rumen fills with fluid and develops a gas cap, and the abomasum accumulates fluid; these give the shape from the rear of pear on the right and apple on the left (papple shape) as seen in the photo. ***PowerLecture: Vagal Indigestion

Answer 153

Answer: **First four weeks postpartum** Explanation This occurs for multiple reasons. Due to the increased metabolic demands from lactation, the diet changes drastically, and more gas is produced in the abomasum. Dairy cows often undergo a period of clinical or subclinical hypocalcemia. Hypocalcemia predisposes to decreased abomasal motility and may be a factor contributing to displacement (especially since there is more gas to move).

Answer 154

Answer: ** By birth of calves persistently infected with BVD due to early-gestation in utero infection with specific types of BVD virus** Explanation Bovine fetuses infected with so-called "non-CPE" BVD virus early in gestation can survive to term and beyond birth as persistently infected (PI) calves. They are thus a source of infection for the remainder of the herd. By definition, a "closed herd" would have little opportunity for exposure to "outside" sources of BVD. Ingestion of feed contaminated with bovine neural tissue is a likely means of spreading bovine spongiform encephalopathy (BSE), but is not known to be a means of transmitting BVD. No role for roundworms as intermediate hosts for BVD has been shown. Co-mingling of dogs and cattle has been shown to transmit Neosprum caninum, but not BVD.

Answer 155

Answer: **The calf appears to have a right brachial plexus avulsion due to traction at birth and it is unknown whether it will improve with time** Explanation The most likely conditions to consider for this calf are brachial plexus avulsion and radial nerve paralysis due to traction at birth. This injury results in an inability to extend the elbow, carpus and fetlock and bear weight on the affected limb with loss of muscle over the shoulder with resultant prominent spine of the shoulder blade. There is a dropped elbow, scuffing of the hooves as the leg is moved forward, and the foot is knuckled over at rest. Depending on the severity of injury, many calves can recover with supportive care. It is often recommended to carefully splint the distal limo to prevent contraction of the flexor tendons. Other differentials could include spinal cord trauma or congenital sarcocystosis. Fractures are less likely given the presentation and lack of pain on palpation.

Answer 156

Answer: **Florenicol SQ, one dose** Explanation One dose of 40 mg/kg florenicol is reported to be an effective therapy and would be favored by a feedlot because the single treatment would avoid costly repeated handling. The use of chloramphenicol is prohibited in cattle in the USA.

Answer 157

Answer: **The mature bull is commonly the reservoir of infection for a herd** Explanation Trichomoniasis, caused by the protozoan Tritrichomonas foetus, is typically a temporary infection in the female. She characteristically eliminates the infection in 2-4 months. The bull, however, becomes a chronic carrier as he ages, since aging is associated with increased depth of epithelial crypts of a bull's glans penis and prepuce, thus increasing the availability of the "niche" where the organism thrives. Once infected, a cow typically clears the infection from the reproductive tract in 2-4 months and regains her fertility. Young bulls are rarely infected chronically, probably because they have shallow penile and preputial crypts, which are thought to provide poor niches for chronic infection. Trichomoniasis typically manifests no visible signs in either the male or female.

Answer 158

Answer: **Cloudy and bloody** Explanation This cow is likely to have acute pyelonephritis. It is most commonly ascending and associated with E. coli, other coliforms, or Corynebacterium renale. You could also use ultrasound to confirm the diagnosis, but finding neutrophils, RBCs and bacteria with these signs is indicative of acute pyelonephritis.

Answer 159

Answer: **Cerebellar hypoplasia** Explanation The correct answer is cerebellar hypoplasia. Microphthalmia and hydranencephaly are also lesions observed with fetal BVD infection, however not as common. Renal dysmaturia is not seen with fetal BVD infection. There are two types of BVD (Type 1 and Type 2) with different surface proteins. BVD virus is also classified as being cytopathic or noncytopathic, based on their behavior in cell culture, but both can cause illness. Interestingly, carrier cattle have been infected with the noncytopathic biotype of BVD as a fetus. ***PowerLecture: Bovine Viral Diarrhea

Answer 160

Answer: **Cochliomyia hominivorax** Explanation The correct answer is Cochliomyia hominivorax. This fly is also known as the screwworm. Females lay hundreds of eggs at the edge of fresh wounds on the cow; the larvae hatch in approximately 24 hours. As the larvae eat the living tissue, they create a huge wound. Screwworm larvae then fall off and pupate, completing their life cycle in approximately 21 days. This fly is reportable!

Answer 161

Answer: **Clostridium chauvoei (blackleg)** Explanation The correct answer is Clostridium chauvoei (blackleg). Clostridium chauvoei results in infection after gaining access to the blood stream via the alimentary tract and then depositing in muscle. This is a serious disease, and animals will die if left untreated. Cattle should be vaccinated at 3 to 4 months of age against this and other Clostridial diseases. Clostridium hemolyticum causes liver lesions, and the toxin results in acute hemolysis and often in death. Clostridioides difficile usually results in gastrointestinal disease in horses. Corynebacterium pseudotuberculosis results in large external bleeding sores on the skin of cattle and boils and internal abscesses in sheep and goats. Mycoplasma bovis can cause sepsis, joint infections and mastitis.

Answer 162

Answer: **Lateral rear digits** Explanation The correct answer is lateral rear digits. Over 80% of foot disease involving the digits involves the rear digits. Additionally, approximately 85% of these involve the lateral aspect. This is because they bear the majority of their rear limb weight on the lateral claw in the hind. In the front, cattle put most of their weight on their medial claw.

Answer 163

Answer: **Hypovolemia, severe metabolic acidosis with hyperkalemia and possible sepsis** Explanation No matter what the causative agent, calves of this age with severe diarrhea develop hypovolemia, severe metabolic acidosis, which results in potassium leaving cells, and the calf becomes hyperkalemic (in plasma). The floppy calf is typical of an animal with severe metabolic acidosis (base deficit of 15 meq or more) and may also be hypoglycemic. This calf is also possibly septic, as bacterial translocation across the gut often occurs in very ill calves.

Answer 164

Answer: **Left displaced abomasum** Explanation LDAs occur most commonly after parturition and should be considered. The ping described is classic for a left displaced abomasum. You can rule out a right displaced abomasum because the ping is described on the left side. Right displaced abomasum is much less common than LDA. There is no mention of stiff gait or xiphoid pain that would indicate a diagnosis of hardware disease. Free gas in the rumen is likely to be heard from the hip to the 8th rib and be a monotone ping. ***PowerLecture: Left Displaced Abomasum

Answer 165

Answer: **Milk fever** Explanation A cow with a history of recent parturition with clinical signs such as these should be considered as having hypocalcemia until proven otherwise. The cow needs treatment to restore normal calcium levels.

Answer 166

Answer: **Utrecht pattern** Explanation The correct answer is the Utrecht pattern. This pattern achieves a nice mucosal and serosal seal when done correctly. Additionally, the exposure of suture to the serosa is minimized with this type of pattern, so adhesions of uterus to surrounding structures is minimized.

Answer 167

Answer: **Bacillary hemoglobinuria** Explanation Also known as redwater, bacillary hemoglobinuria is caused by germination of Clostridium Novyi type D spores in the liver after anaerobic damage by migrating liver fluke larvae. Cl. Novyi was formerly called Cl. hemolyticum. Vaccination can prevent this disease. ***PowerLecture: Flukes and Bacillary Hemoglobinuria

Answer 168

Answer: **Ivermectin in early fall** Explanation This is a cattle warble called Hypoderma. The 2 species are H. bovis and H. lineatum. They undergo a long migration in tissues and only emerge from the back of the animal in spring. The crucial treatment time is early fall when larvae are just beginning to migrate in tissues. Organophosphates or one of the macrocyclic lactones (ivermectin, doramectin, eprinomectin or moxidectin) are effective.

Answer 169

Answer: **3-Methylindole** Explanation The correct answer is 3-methylindole. Cattle that are moved to lush forage that is high in tryptophan metabolize the tryptophan to 3-methylindole in the rumen. The 3-MI is toxic to the lung, resulting in acute interstitial pneumonia and emphysema. This syndrome is known as acute bovine pulmonary edema and emphysema (ABPEE), fog fever or grunts. 4- Ipomeanol is the chemical involved in moldy sweet potato poisoning, which looks clinically similar to this.

Answer 170

Answer: **Hydrops allantois (hydroallantois) is a disorder of the placenta and the prognosis for life of the fetus and fertility of the cow is poor** Explanation The clinical description is most consistent with hydroallantois because of the rapid accumulation of fluid and the clinical signs of the cow. Hydramnios is a reasonable differential although it more typically involves gradual accumulation of fluid and the cow is usually clinically unaffected. Hydroallantois is a disorder of the placenta (chorio-allantois) that results in rapid accumulation of 100-200 liters of watery, clear fluid during the last trimester. The cow develops a rounded appearance to the abdomen and it is usually not possible to palpate the fetus or placentomes. The cow often becomes sick with anorexia, decreased rumen motility, dehydration and weakness. She may go down or rupture the prepubic tendon. The prognosis for the fetus is guarded and even with treatment, the cow will likely be infertile. Induction of parturition or C-section are treatment options but the majority of calves are not viable and the dam rarely has normal colostrum. If the pregnancy is terminated, it is unlikely that the cow will have a productive milk cycle. Usually salvage for slaughter is the preferred option unless the fetus is considered valuable and the cow is near term. Hydramnios is a disorder of the fetus, and the placenta itself is normal. The condition is typically characterized by gradual accumulation of thick viscous fluid during the later part of gestation. The cow develops a pear shaped caudal view. The fetus and placentomes are usually palpable and the cow is usually clinically well. Pregnancy usually goes to term and a small, deformed fetus is delivered. The cow has a fair to good prognosis for life and fertility. The cow may be induced or allowed to go to term depending on her condition.

Answer 171

Answer: **Decreased serum chloride and metabolic alkalosis** Explanation The correct answer is decreased serum chloride and metabolic alkalosis. This occurs as a result of the intestines not being able to reabsorb chloride back into the blood stream after it is secreted into the abomasum. Chloride is a strong anion and results in metabolic alkalosis when it is decreased. ***PowerLecture: Vagal Indigestion

Answer 172

Answer: **SCC is normal** Explanation The correct answer is the somatic cell count is normal. The problem that is causing the decreased milk production does not appear to be associated with mammary gland infection. Many studies suggest that cows with SCC of less than 200,000 are not likely to be infected with major mastitis pathogens, but cows with SCC above 300,000 are probably infected (Smith, 1996). Herds with bulk tank SCC above 200,000 have varying degrees of subclinical mastitis. At 500,000 SCC, approximately 16% of the mammary quarters may be infected, resulting in a 6% reduction in milk production compared to a SCC of 200,000.

Answer 173

Answer: **Gunshot** Explanation According to the AVMA Guidelines for the Euthanasia of Animals, gunshot is the most common method used for on-farm euthanasia of cattle. The anatomic landmarks used for the point of entry should be the intersection of two imaginary lines drawn from the outside corner of the eye to the center of the base of the opposite horn (or equivalent position). The person euthanizing the animal should have sufficient training and experience with the firearm for a safe and accurate procedure. Although one well-placed bullet usually results in immediate loss of consciousness with little likelihood of return to consciousness, one should always be prepared to deliver a second or even a third shot if necessary. Unacceptable methods for euthanasia of conscious animals include injection of chemical agents (disinfectants, electrolytes including potassium chloride, and nonanesthetic pharmacologic agents), drowning, air embolism, electrocution, and exsanguination. Administration of xylazine or other alpha-2 agonists followed by intravenous potassium chloride or magnesium sulfate is also considered unacceptable because alpha-2 agonists alone are recognized as being unreliable for producing generalized anesthesia although they can produce a state resembling it. Ref: AVMA Guidelines for the Euthanasia of Animals: 2013 Edition

Answer 174

Answer: **Winter dysentery** Explanation Winter dysentery is an epidemic disorder of housed cattle, usually occurring in cold months and affecting 10-90% of adult cows. If fever occurs at all, it usually precedes the diarrhea phase. The disease is thought to be caused by coronavirus, and lesions involve the colon. In typical outbreaks, the disease runs its course in weeks and the herd becomes immune and recovers, although milk production may not recover to previous levels. With Salmonella typhimurium, the cows would be sicker, febrile, have abnormalities in the CBC compatible with endotoxemia (neutropenia or neutrophilia), and an increased plasma fibrinogen. In a severe Salmonella typhimurium outbreak, some cows would likely die. The scenario described is not compatible with a diagnosis of Johne's disease. Although a few individual animals in a herd might develop type 2 Ostertagia, a herd outbreak would be highly unlikely, especially involving older cows. With Clostridium perfringens type A, there is a low morbidity and high mortality; signs of small intestinal obstruction develop, and if feces are passed they are very dark and bloody.

Answer 175

Answer: **Calf diphtheria** Explanation Also called necrotic laryngitis, or laryngeal necrobacillosis, this mainly feedlot condition strikes randomly but can result in death or a permanently misshapen larynx. The causes appear to be Histophilus somni and Fusobacterium necrophorum. ***PowerLecture: Upper Respiratory Disease

Answer 176

Answer: **Teeth** Explanation The correct answer is teeth. Fluoride toxicity results in ameloblasts prematurely reducing in size. Eventually, the enamel epithelium forms an irregular matrix which does not calcify normally. Fluoride toxicity will cause bone lesions. Interestingly, the first palpable lesions are seen on the medial surface of the proximal third of the metatarsal bones. A key thing to know is that articular surfaces are not affected with osteofluorosis so this may help rule it in or out from other diseases such as osteomyelitis, septic arthritis, and osteoarthritis.

Bovine Flashcards

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