Diseases of the GI Tract Flashcards
(47 cards)
What is diarrhea?
An increase in frequency of defecation or fecal volume
Volume is increased by water content
It is diarrhea when more water is excreted than absorbed
What are the 2 types of diarrhea?
Malabsorptive and secretory
What causes malabsorptive diarrhea?
Damage to villous epithelium and loss of enterocytes leading to shrotening of the villi because loss is faster than replacement
What 2 events are the pathogenesis of malabsorptive diarrhea?
- Decreased surface area reduces absorptive ability of intestines
- Mature enterocytes are lost, as well as their digestive enzymes, resulting in a loss to absorb water
–> commonly caused by bacteria, virus, protozoa
What is secretory diarrhea?
When water secretion is greater than can be absorbed
What are some causes of secretory diarrhea?
Usually from hypersecretion from small intestinal crypts due to abnormal stimulation
■ This stimulation increases
adenyl cyclase activity & production of cAMP within the cells, resulting in opening chloride gates & secreting water, electrolytes, and bicarbonate
■ Most commonly caused by enterotoxins such as those produced by gram negative bacteria (ETEC) and sometimes rotavirus.
■ This type of diarrhea is more common in neonates.
■ Occasionally see ETEC in adults
What are the most common types of Salmonella inn cows?
S. enterica serotypes typhimurium, dublin (host adapted), newport
5-20% of cows estimated to carry Salmonella
What are some clinical signs of Salmonella?
Systemic Signs of endotoxemia ■ Fever ■ Tachypnea ■ Tachycardia ■ Scleral injection (red eye) ■ Weakness ■ Rumenstasis ■ Maldigestion –Loss of mucosal epithelial cells ■ +/-Secretory –Enterotoxin production
How can you treat/ prevent Salmonella?
Treat = fluids, NSAIDs, antibiotics (C/S) Prevention = management, control Clostridium
What is the causative agent of Johne’s Disease?
Mycobacterium avium ss. paratuberculosis
80% herd prevalence in the US
How is Johne’s Disease transmitted?
- Ingestion is primary route –> manure, contaminated milk, water, feed
- Intrauterine also spreads to 25% of calves
What are the clinical signs of Johne’s Disease?
- Persistent and treatment-resistant diarrhea
- Rapid weight loss with good appetite
- No fever
- Bottle jaw due to potential protein losing enteropathy in dairy cattle ages 3-5
What are the stages of infection in Johne’s animals?
- Advanced clinical disease (severe emaciation, diarrhea, bottle jaw, wasting)
- Clinical (weight loss, diarrhea, decreased milk production)
- Subclinical (bacteria present and shedding but no clinical signs)
- Silent (no apparent disease and not shedding)
How can you diagnose Johne’s disease?
- Culture manure, tissue, environment
- PCR/ ELISA/ AGID on milk or blood
How can you prevent Johne’s disease?
- Test herd with ELISA
- Confirm disease with PCR
- Eliminate shedding animals
- Retest every 6-12 months
What is the causative agent of winter dysentery?
- Bovine coronavirus
- Sensitive to heat and common disinfectants, though survives cold temps
- can withstand low pH, so survives in gut
How is winter dysentery transmitted?
- Fecal-oral route most common
- Wild ruminants are reservoirs
- Highest age risk between 2-6 years old
- high morbidity, low mortality**
What are the clinical signs of winter dysentery?
- Anorexia, fever, liquid/ bloody diarrhea, respiratory signs, decreased milk production
How do you diagnose winter dysentary?
Electron microscopy, ELISA, RT-PCR on intestines, feces, rectal or nasal swabs
must collect within 1-3 days of onset of diarrhea
How do you treat winter dysentery?
- Fluids, antibiotics
- No proven vaccine
- Clinical signs may persist
Which Clostridium causes myonecrosis?
Clostridium novyi Type A
- Results in a very edematous wound caused by the alpha toxin
- Causes “bighead” in rams
Which clostridium causes “Black Disease”?
Clostridium novyi type B
- Results in infectious necrotic hepatitis –> highly fatal in well nourished adult (2-4 yo) sheep
- Peracute death most common (1-2 HOURS sheep, 1-2 DAYS cattle), will see venous congestion on ventral skin
What clostridium causes bacillary hemoglobinuria?
- Clostridium novyi type D AND Clostridium hemolyticum
- infection occurs after infection with Fasciola hepatica**
- Occurs in pastures with poor drainage
- Affects well-nourished calves > 1 year
What are the clinical signs of bacillary hemoglobinuria?
–Peracute = death
– Tachycardia, tachypnea,
inappetance, agalactia, pale mm, +/-fever, severe anemia
– Hemoglobinuria = red water
