Diseases of the GI Tract Flashcards
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
What are gross lesions associated with bacillary hemoglobinuria?
Subcutaneous edema, petechial/ ecchymosis
** Hepatic infarcts are pathognomonic **
What clostridium causes Braxy?
Clostridium septicum
What is the clinical progression of braxy?
Initially warm, malignant edema, hemorrhage occur around the wound and eventually spreads down the fascial plane, becoming cold
What clinical signs does the enteric form of braxy have?
Causes hemorrhagic necrotizing abomasitis in lambs
Other clinical signs include depression, fever, colic, tympany
fatality can reach 100%
Which clostridium causes clostridial enterotoxemia?
Clostridium perfringens
- Normally found in the intestines disease occurs when bacteria and toxins accumulate
- Types A,C,D in USA; B found everywhere else; Type E uncommon
How do you prevent Clostridial agents?
Give vaccines and toxoids!
What is hemorrhagic bowel syndrome?
A frequently fatal disease of dairy cattle lactating 3-4 months –> blood clots from hemorrhage creates intestinal obstructions
Associated with Clostridium perfringens Type A
What are the clinical signs of hemorrhagic bowel syndrome?
Peracute progressive weakness and abdominal distention (can be mistaken for other obstructions)
Rectal exam appears basically normal
Transabdominal US shows dilated loops of intestine
24-48 hours = dead or septic shock
How do you treat Hemorrhagic bowel syndrome?
Treatment usually
unrewarding
Medically: supportive care
Surgically: remove effected bowel
Where does blister buttercup grow?
Grows early spring near bodies of water/ wet areas across the US
What is the toxin in blister buttercup?
Ranunculin, a glycoside eventually converted to protoanemonin
Results in orally irritation and gastroenteritis
CS include excessive salivation, reddened oral mucosa, diarrhea +/- blood
What are the toxins in pokeweed and what are its clinical signs?
Toxins are saponins, oxalates, and alkaloid phytolacine
CS include severe bloody diarrhea, colic, excessive salivation, death
What are the toxins in coffee weed/ Sesbania and what are its clinical signs?
Found throughout US grow in damp soil
Green seeds most toxic and remain so for years
CS include severe GI irritation, liver degeneration, hemorrhagic diarrhea, death
Treat with laxatives and activated charcoal
What are lectins?
Glycoproteins that bind to cell receptors resulting protein synthesis inhibition and cell death
Found in seeds and are very toxic
What are the 3 main lectins
Ricin (castor bean), abrin (rosary pea), robinin (black locust) new growth most toxic
2g/kg castor bean feed is lethal to cattle intestinal irritation and profound purgation
Animals eventually die of hypovolemic shock
How do you treat lectin poisoning?
- Activated charcoal
- MgOH
- IV fluids
What is the principle toxin in box shrubs?
Toxic alkaloids causing severe gastroenteritis, colic, hemorrhagic diarrhea
Cattle are exposed from discarded clippings
What are some causes of rectal prolapse?
Tenesmus, dysuria, neuropathy, chronic coughing, genetics
What is a grade I rectal prolapse?
Rectal mucosa prolapses. Small, intermittent, and common
What is a grade II rectal prolapse
All layers of rectum prolapse. Common
What is a grade III rectal prolapse?
Same signs as Type II although the large intestine prolapses as well. Uncommon
What is a grade IV rectal prolapse?
Type III with an intact anal sphincter resulting in rectal/ intestinal constriction. Rare
How do you treat rectal prolapse?
Purse string suture with umbilical tape for 5-10 days –> give an epidural to stop straining
Surgical amputation
Rectal ring
Treat underlying cause!!!!!!!!!!!!!!!!!!!!!!!
