Unit 2 - Diarrhea Flashcards
What is diarrhea?
Passage of feces with increased water content
What is colitis?
inflammation of the large bowel
What is the duration of acute diarrhea?
1-2 weeks
What is the duration of chronic diarrhea?
greater than 1 month
What are the infectious etiologies of acute diarrhea in a horse?
Salmonella, Neorickettsia, Clostridium, and Cyanthostomiasis
What else can cause acute diarrhea?
antimicrobial induced and toxin induced
What is one of the most common causes of severe infectious diarrhea in horses?
Salmonella
What is the most commonly isolated Salmonella species?
Salmonella typhimurium (most common), S. agona, S. anatum, S. krefeld
What percentage of the horse population are non-systomatic carriers of Salmonella?
3-5%
How is Salmonella spread?
It is contagious - spread by direct contact and fomite transmission
What predisposing factors may induce Salmonella diarrhea?
Stress, general anesthesia, systemic illness, prolonged transportation, administration of antimicrobials, or exposure to a horse with acute Salmonella-induced colitis
What is severity of Salmonella induced diarrhea related to?
The Salmonella species involved, age, and health status of the animal
What are the four clinical presentations of Salmonella?
- Asymptomatic carriers
- Fever, depression, neutropenia, anorexia, without evidence of diarrhea
- Severe, profuse diarrhea with dehydration, neutropenia, and endotoxemia
- Chronic diarrhea
What clinical signs are associated with Salmonella diarrhea?
Acute severe and profuse diarrhea, dehydration, +/- abdominal pain, tachycardia, tachypnea, fever, depression, and anorexia
What clinical pathology abnormalities are associated with Salmonella induced diarrhea?
Leukopenia, neutropenia, left shift, hemoconcentrationn, electrolyte derangements, azotemia, hypoproteinemia, and metabolic acidosis
How is Salmonella induced diarrhea diagnosed?
Clinical signs and/or history of exposure, serial cultures of feces (at least 3 negative), PCR of feces
How is Salmonella induced diarrhea treated?
Overall treatment for acute diarrhea and supportive care
What does Neorickettsia risticii cause?
Potomac Horse Fever
What does Neorickettsia risticii infect?
the equine macrophage
What cells does Neorickettsia risticii have tropism for?
cells of the cecum and large colon
Where does Neorickettsia risticii survive?
In cell-derived vacuoles
How is Neorickettsia risticii transmitted?
It is not completely understood, but there is some associated between disease and proximity to freshwater streams and rivers
When does Neorickettsia risticii transmission typically occur?
during spring/summer months in northern climates
What clinical signs are associated with Neorickettsia risticii induced diarrhea?
Soft stool to profuse diarrhea, dehydration, +/- abdominal pain, tachycardia, tachypnea, fever, depression, diarrhea, laminitis
What clinical pathology changes are associated with Neorickettsia risticii infection?
Electrolyte deficiencies, metabolic acidosis, hypopriteinemia, azotemia, leukopenia, and neutropenia with a left shift (toxic changes)
How is Neorickettsia risticii diagnosed?
PCR tests (feces and blood) or paired blood samples for antibody titers
How is Neorickettsia risticii treated?
Supportive therapy and oxytetracycline
What is the prognosis for Neorickettsia risticii infection?
Fair to good; mortality rate is 5-30%
How is Neorickettsia risticii prevented?
vaccination (efficacy debatable); natural infection protects for 1-2 years
What type of bacteria is Clostridium?
Obligate gram + anaerobe
What Clostridium species are the most commonly implicated in causing acute diarrhea?
Clostridium difficile and Clostridium perfringens
What toxins does C. difficile produce?
Toxin A and Toxin B
What effects does Toxin A have?
Intestinal secretory and cytotoxic effects, increases intestinal permeability, and activates inflammatory cells
What effects does Toxin B have?
Enterotoxigenic and secretory effects
What toxins does C. perfringens create?
Toxin A and C
What unique clinical sign does Clostridium cause that other acute diarrhea agents dont?
Gas distention
How is acute diarrhea caused by Clostridium diagnosed?
ELISA toxin assay or culture of feces
How is Clostridium diarrhea treated?
Supportive care and Metronidazole
How do Cyathostomes cause diarrhea?
The emergence of large numbers of L4 stage larvae from the mucosa of the cecum and colon damages the submucosa/mucosa and provokes a severe granulomatous reaction
When does Cyathostome caused diarrhea typically occur?
Late winter and spring
What intestinal ‘disease’ is associated with Cyathostomes?
Hemorrhagic or fibrinous typhlitis (cecum-itis) and colitis
What are the distinguishing featurse of Cyathostome induced diarrhea?
Profound hypoalbuminemia, larvae found on scrape or biopsy, and chronic changes (weight loss, ill thrift, ventral edema, intermittent fever, and intermittent colic)
How is Cyathostome induced diarrhea treated?
Fenbendazole, Moxidectin, and supportive care
How can antimicrobials cause acute diarrhea?
They cause changes in the normal GI flora leading to the diarrhea
What is the prognosis for antimicrobial induced acute diarrhea?
Poor - it is often fatal
What drugs can cause antimicrobial induced acute diarrhea?
Trimethoprim suflas, erythromycin, tetracyclines, ceftiofur, and potassium penicillin
What NSAIDs can cause toxin induced acute diarrhea?
Phenylbutazone and flunixin meglumine
What disease processes can NSAID toxicity cause?
right dorsal colitis or gastric ulceration
What clinical signs are associated with right dorsal colitis?
Intermittent colic, diarrhea, lethargy, +/- fever, hypoproteinemia, ventral edema, and history of NSAID use
What will you find on ultrasound in patients with right dorsal colitis?
Thick or edematous colon wall
How is right dorsal colitis treated?
Discontinue use of NSAIDs, low bulk feed, sucrulfate, Misoprostol, and Psyllium
Why can overfeeding/grain overload cause diarrhea?
It overwhelms the small intestinal digestive capacity - excess CHO enter colon, rapidly fermented by lactic acid producing bacteria, decreases the pH and kills gram negative bacteria, endotoxemia
How is diarrhea caused by overfeeding/grain overload treated?
Lavage and remove gastric contents, anti-endotoxin therapy, fluid therapy, Cathartics, activated charcoal, laminitis treatment/prevention, possibly surgical removal
What diagnostics should be performed in all cases of acute diarrhea?
CBC, serum chemistry, venous blood gas (acid/base), and fecal samples
What supportive care should be considered/given in all cases of adult equine diarrhea?
IV fluid therapy, oral fluids + electrolytes, anti-inflammatories, medications to modulate endotoxemia, nutritional support, prevention of laminitis, colloids, and correction of acidosis
What is the maintenance rate for IV fluids for adults?
50 ml/kg/day
What medications can be given to modulate endotoxemia?
Flunixin meglumine, hyper immunized plasma, polymyxin B, and pentoxifylline
What probiotic can be given to treat adult equine diarrhea?
Saccharomyces boulardii
What nutritional support can be given in cases of adult equine diarrhea?
Ground up pellets via NG tube, IV dextrose, partial parenteral nutrition, and total parenteral nutrition
What preventative measures can be attempted to prevent laminitis in patients with diarrhea?
Ice boots, NSAIDs, mechanical support, Acepromazine, and Aspirin
Why would you want to give colloids in a patient with diarrhea?
To maintain vascular oncotic pressure and prevent edema
How do you correct metabolic acidosis in patients with diarrhea?
Correct with NaHCO3
What are the potential causes of chronic diarrhea?
Diet, inflammatory bowel disease, primary disorders of other body systems, intestinal parasites, infectious causes, sand enterocolitis, and miscellaneous
How could diet cause chronic diarrhea?
Excess amounts of CHO, oil, supplements, fresh green grass, and toxic plants
What inflammatory cells could cause IBD which could cause chronic diarrhea?
granulomatous, eosinophilic, and lymphocytic-plasmacytic
What clinical signs are associated with inflammatory bowel disease?
Colic, weight loss, hypoproteinemia, and abnormal glucose absorption
How do you do a glucose absorption test?
Fast overnight, give 1g/kg of dextrose in water. Measure BG every 30 minutes for 4 hours. Peak BG should be 2x the baseline at 60-120minutes
How do you diagnose IBD?
rectal biopsy, clinical signs, and clin path abnormalities
How do you treat IBD?
corticosteroids
What primary disorders of other body systems cause chronic diarrhea?
Liver disease/cirrhosis and congestive heart failure
What intestinal parasites can cause chronic diarrhea?
Large or small strongyle species
What infectious causes can cause chronic diarrhea?
Chronic Salmonella infections
How does sand cause chronic diarrhea?
It irritates the ventral colon and causes inflammation of the mucosa leading to subsequent diahhrea
What miscellaneous things can cause chronic diarrhea?
peritonitis, abdominal abscess, and lymphosarcoma of the GI tract
What diagnostics should be considered for patients with chronic diarrhea?
rectal palpation, abdominocentesis, CBC and chemistry profile, fecal analysis, rectal biopsy, intestinal absorption test, abdominal radiography, abdominal ultrasonography, investigate medications/supplements received, diet
How is chronic diarrhea treated?
treat the underlying cause, corticosteroids, and diet
What is the prognosis for chronic diarrhea?
poor
