Horses Flashcards
(120 cards)
what does urine scalding (+incontinence) indicate?
ectopic ureter
90% cases are fillys (young)
A 9-year old Standardbred stallion comes to see you for evaluation of muscle atrophy. You examine the horse and note atrophy of the lateral thigh and gluteal muscles. When the horse is backed up, spasmodic hyperflexion of either hindlimb occurs resulting in a high-stepping gait. Which of the following is most likely responsible for the observed signs?
Red maple intoxication Castor bean intoxication Black walnut intoxication Sweet pea intoxication Senecio or groundsel intoxication
This case describes a horse with stringhalt or sudden flexion (contraction of the lateral extensor tendons) of one or both hind legs. It is most evident when the horse is backing up slowly or turning. It can involve one or both hind legs. The etiology in some cases is unknown but the condition can be associated with chronic intoxication of sweet peas (Lathyrus spp.). Australian stringhalt has been associated with flatweed ingestion (Hypochoeris radicata). The precise pathogenesis is not understood, but a mycotoxin affecting the long myelinated nerves in the hind limbs has been suggested based on the types of nerve damage seen in affected horses.
Black walnut intoxication is associated with laminitis and colic after exposure to wood shavings of black walnuts. Red maple intoxication is associated with acute hemolytic anemia. Senecio or groundsel intoxication is associated with liver disease after chronic exposure. Castor bean intoxication is associated with severe gastrointestinal irritation and hemorrhagic diarrhea.
A 9-month old foal presents with difficulty walking. You immediately note that the foal appears to have a flexural deformity of the right forelimb consisting of an increased dorsal hoof wall angle of 80 degrees such that the heel does not contact the ground. The coronary band is prominent. You take radiographs which confirm a broken forward hoof-pastern angle. What is the most appropriate treatment for this type of flexural limb deformity?
Superior check ligament desmotomy
Lateral digital extensor tenectomy
Desmotomy of the accessory ligament of the deep digital flexor tendon
Transection of the insertion of the semitendinosus
This case describes a severe flexural deformity of the distal interphalangeal joint, also known as “clubfoot”. This is typically a congenital condition in young horses although it can be acquired. A genetic component is suspected. Mild cases can sometimes be managed conservatively with NSAIDs, farriery, exercise and nutritional changes. Severe cases often require surgery; the surgical procedure of choice is desmotomy of the accessory ligament of the deep digital flexor tendon (also known as inferior check ligament desmotomy). The accessory ligament of the deep digital flexor tendon (inferior check ligament) runs from the palmar surface of the proximal metacarpus to the deep flexor tendon in the mid-metacarpal region.
The superior check ligament originates above the knee and attaches to the superficial flexor tendon, and its primary purpose is to support the tendon. Superior check ligament surgery is used to treat a bowed tendon.
Lateral digital extensor tenectomy is a procedure used to treat stringhalt. Transection of the insertion of the semitendinosus is used to treat fibrotic myopathy.
duration mare estrus? 1d 12h 20d 6d 14d
6 days
Many times, horses require additional muscle relaxation during anesthesia. Which of the following is commonly used for its property of being a centrally acting muscle relaxant?
Guaifenesin
Ketamine
Atracurium
Succinylcholine
The correct answer is guaifenesin. Unfortunately, the exact mechanism is unknown; however, we do know that guaifenesin acts centrally by blocking nerve impulse transmission at the internuncial neuron level in the subcortical brain, brain stem, and spinal cord. Veterinarians should be careful not to give too much guaifenesin because early signs of toxicity are in the form of increased rigidity. So what does the vet do? Give more guaifenesin, causing respiratory and cardiac arrest. Ketamine is a dissociative agent and is known for its ability to cause hypertonia. Atracurium is a non-depolarizing neuromuscular blocking agent that acts by competitively binding to cholinergic receptors at the motor endplate. Succinylcholine is a depolarizing neuromuscular blocking agent.
In the Spring of 2001, a syndrome later termed Mare Reproductive Loss Syndrome, MRLS, occurred in central Kentucky. This syndrome was characterized by early and late-term fetal loss, fibrinous pericarditis, neonatal foal death and unilateral uveitis. Which of the following was incriminated as a likely potential cause of MRLS?
a. Exposure or ingestion of red maple leaves
b. Exposure or ingestion of Japanese yew
c. Exposure or ingestion of black walnut
d. Exposure or ingestion of blister beetles
e. Exposure or ingestion of eastern tent caterpillars
The correct answer is exposure or ingestion of eastern tent caterpillars. The exact pathogenesis of MRLS is still unknown, but the presence of eastern tent caterpillars was strongly associated with the disease. Later, experimental studies in which pregnant mares were exposed to or fed eastern tent caterpillars resulted in early and late fetal loss.
Most equine uroliths are composed of which of the following substances?
Magnesium ammonium phosphate Calcium oxalate Calcium carbonate Cysteine Phosphate
The correct answer is calcium carbonate. Equine urine contains high amounts of calcium carbonate. Magnesium ammonium phosphate (aka struvite crystals) is also occasionally noted in horse urine.
You are examining a 2-year old pony with lameness that worsens after activity or work. The pony displays mild lameness on your exam and is sensitive to deep palpation of the third metacarpal bone of the left front limb. Radiographs reveal periostitis and new bone formation along the second metacarpal bone. No fracture is present. What term describes this condition?
Splints Thoroughpin Osselets High ringbone Sidebone
This is a description of splints or metacarpal exostosis which involves periostitis of the interosseous ligament between the third and second metacarpal (or metatarsal) bone. Treatment usually involves rest and anti-inflammatory medications, although if the bony exostoses impinge on the suspensory ligament, surgical removal of the proliferative tissue may be indicated.
Sidebone refers to ossification of the alar cartilage of the coffin bone. High ringbone refers to osteoarthritis of the proximal
interphalangeal (pastern) joint. Osselets are inflammation of the periosteum on the dorsal distal epiphyseal surface of the third metacarpal bone and fetlock joint. Thoroughpin is the term for effusion of the tarsal sheath (sheath of the deep digital flexor).
Horses are predisposed to developing enteroliths in California. What food item is considered to be playing a role in the formation of enteroliths?
Sweet feed
Alfalfa hay
Grass hay
Oat hay
The correct answer is alfalfa hay. Alfalfa hay in California is thought to be particularly high in magnesium. This may be a predisposing factor which results in magnesium ammonium phosphate enteroliths.
What is the most common cause of colic in a newborn foal?
Salmonella Meconium impaction Correct Answer Strongylus vulgaris Parascaris equorum Nephrosplenic entrapment
The correct answer is meconium impaction. Meconium impaction occurs in the rectum or small colon. Clinical signs include straining, swishing of the tail, and restlessness. Rectal examination reveals numerous hard fecal balls. Treatment consists of an enema with water and a mild soap. Meconium is the first intestinal discharges of the newborn foal, consisting of epithelial cells, mucus, and bile.
A 12-year old mare presents for a sudden onset of ptyalism and an inability to prehend food. Where is the lesion?
a. Corpus callosum and amygdala
b. Substantia nigra and globus pallidus
c. Caudal cerebellar peduncle and medial longitudinal fasciculus
d. Lateral lemniscus and rostral olivary nucleus
b. The correct answer is substantia nigra and globus pallidus. A lesion to these basal ganglia will result in movement disorders. Particularly, yellow star thistle poisoning will lead to an inability to prehend food in horses. The corpus callosum connects the two cerebral hemispheres together, and the amygdala is involved with fear and memory. The caudal cerebellar peduncle connects the medulla to the cerebellum and is involved in transmission of signals pertaining to movement. The medial longitudinal fasciculus is involved in conjugate gaze. The rostral olivary nucleus and lateral lemniscus are both involved in auditory pathways.
The 3-year old stallion in the photo was recently treated by you for Strangles. He is now in isolation and the owner would like to know when he can safely reintroduce the horse to his stable. Which of the following should you tell the owner?
a. It is best to wait for 30 days after resolution of signs and then perform 3 consecutive weekly negative nasopharyngeal cultures
b. It is never safe to reintroduce the horse because most horses become lifelong carriers and shed the organism
c. He should vaccinate all of the horses at his stable and then reintroduce the horse 3 weeks later
d. It is best to wait until the horse has negative serology to antibodies against the SeM virulence factor
e. Fortunately, Strangles is not contagious to other horses
a. Strangles can be a difficult disease to control and vigilant preventative measures are necessary to minimize transmission as a small percentage of horses develop persistent infection of the guttural pouches associated with purulent inflammation or the presence of chondroids. These carriers can be detected either by culture or by detection of S. equi DNA using the polymerase chain reaction (PCR) test. PCR is a more sensitive test but also more expensive and may have false positives in recently infected horses due to residual DNA from dead bacteria.
Investigation of carriers should be done either before a new animal is introduced into a stable or herd, or at least 30 days following recovery of a horse from strangles. Animals should be isolated until there have been 3 consecutive weekly negative cultures and/or PCR reactions.
If an animal is positive, endoscopic evaluation of the guttural pouch is recommended, chondroids removed, and guttural pouches treated by flushing and infusing 5 million units of penicillin G in 3% gelatin. In addition, these horses should be treated with penicillin G intramuscularly for 7 days, isolated for 30 days, and then retested with the 3 consecutive series of nasopharyngeal swabs and culture.
You should note that even this diligent recommendation is not 100% fail-safe. However, this is still the best answer choice. It is not true that most horses become lifelong carriers as this applies to <10% of horses. Waiting 90 days after resolution without testing or retreating is not recommended.
Vaccines against S. equi are available; there are intramuscular and intranasal vaccines available. The intramuscular vaccine is associated with pain and abcessation at the vaccine site as well as purpura hemorrhagica. The killed vaccine does not provide complete protection but it does reduce the severity of clinical illness. A live, attenuated S. equi vaccine has been introduced as an intranasal vaccine for the prevention of strangles. It is strongly recommended that other vaccines or injections not be administered at the same time as the intranasal vaccine. Since the live organism may persist in the nose, control measures that involve detection of carriers may not be effective in horses immunized with this vaccine.
Serology is best for determining the exposure status of a horse and is mainly used to aid in the diagnosis of purpura hemorrhagica and bastard strangles.
Guttural pouch infections in the horse may result in pharyngeal paresis and food may reflux from the nose because:
a. The epiglottis does not close normally against the rima glottidis.
b. The soft palate no longer seals normally against the roof of the nasopharynx.
c. The upper esophageal sphincter remains open.
d. The tongue fails to engage the hard palate.
e. The arytenoid cartilages fail to seal the glottis.
b. In normal swallowing, the soft palate moves dorsally to contact the roof of the nasopharynx and occlude the nasal passages such that food cannot reflux. This reflex is lost when cranial nerves 9 through 12 are inflamed or damaged in the guttural pouch due to infection. Mycotic infection is most frequently the cause.
All of the other answers except for the choice about the upper esophageal sphincter are also things that happen with pharyngeal paresis, but they are not responsible for feed refluxing from the nose. The epiglottis and arytenoids abnormalities result in coughing and aspiration of food into the larynx. Tongue problems result in food being dropped from the mouth during chewing and/or difficulty moving the food bolus to the pharynx for swallowing. If the upper esophageal sphincter remains open, there would be few clinical signs; that alone would not result in food refluxing from the nose.
A 3 month old Arabian foal presents for a progressive onset of intention head tremors, ataxia, dysmetria, and spasticity. On physical exam, the foal is noted to have proper mentation and is not weak. Heart rate, respiratory rate, and temperature are within normal limits. Given the signalment and presentation, what is the most likely diagnosis?
Inner ear disease
Cerebellar abiotrophy
Sarcocystis neurona
Cerebellar dysplasia
b. The correct answer is cerebellar abiotrophy. Cerebellar abiotrophy is usually observed in foals which are less than one year of age, particularly 1-6 months of age. Cerebellar abiotrophy is the most common cerebellar disease found in horses. It is mostly seen in Arabian, Oldenburg, and Gotland breeds. There is no treatment, and signs may be progressive. Diagnosis is based on a good history and clinical signs such as intention tremors, lack of a menace, hypermetria, and ataxia.
Which of these conditions is associated with excess dietary calcium and vitamin D in young horses?
Osteochondrosis
Nutritional secondary hyperparathyroidism
Goiter
Rickets
The correct answer is osteochondrosis. Rickets and nutritional secondary hyperparathyroidism are caused by calcium deficiency or excess phosphorus. Goiter is caused by insufficient or excess iodine.
causes of dysphagia in horses
tetanus
guttaral pouch mycosis
rabies
what does auriculopalpebral block?
motor innervation to orbicularis oculi
horse cant prehend, lips pulled back, tongue tremors
yellow star thistle
normal finding in (race)horses with bradycardia as result of high vagal tone
1st or 2nd degree AV block
PPID
pituitary adenoma
horses >15yrs
plasma ACTH high (or TRH stim)
tx: pergolide(suppresses pituitary secretion)
(*hirsutism, PU/PD, laminitis, lethargy, sweating/lactation, loss of muscle, infertility, infection -tooth root abscess)
Equine infectious anemia
- test with coggins - IMMUNODIFFUSION
- immunodeficiency virus transmitted by bloodsucking flies and contaminated instruments
Where do they lay eggs?
- horse bot
- flea
- pinworm
- stomach worm
- horse bot - ANYWHERE, gasterophilus usually have yellow eggs CANNON BONE
- flea - not in horses
- pinworm- PERINEUM
- stomach worm (habronema) eggs in feces
Which of these viruses are normally found in the upper respiratory tract of the horse?
Equine viral arteritis virus
Equine influenza
Equine adenovirus
Equine herpesvirus
The correct answer is equine adenovirus. Adenovirus is normal in the upper respiratory tract but can cause a lower respiratory tract infection in immunocompromised individuals, particularly foals with failure of passive transfer or combined immunodeficiency. In fact, adenovirus is the most common cause of death in foals with those two conditions, leading to an often fatal pneumonia.
You diagnose this 15-year old mare in the picture with a mild, acute laminitis. Which of the following can be used as treatment for this horse?
Application of horse shoes
Prednisone
Phenoxybenzamine
Trimethoprim sulfa
The correct answer is phenoxybenzamine. Phenoxybenzamine is an alpha-adrenergic antagonist promoting vasodilation and restoration of blood flow to the digits. Prednisone is contraindicated in laminitis because corticosteroids are believed to induce the condition. Antibiotics are not indicated unless a secondary bacterial infection develops. Application of a horse shoe would not help and would be very painful in an already sensitive and painful condition. Other medications used to restore blood flow to the digits include acepromazine, isoxsuprine hydrochloride, dimethylsulfoxide (DMSO), heparin, and nitroglycerine.
