Diarrhoea Flashcards
What is the average faecal output of a horse? When might this increase (non-pathologically)?
1kg every 2hrs (~12kg a day) May increase 20-28kg a day if fed grass hay / oats
What are the 5 basic mechanisms of diarrhoea?
- Malabsorption 2. Increased secretion 3. Decreased transit time (abnormal motility) 4. Osmotic overload 5. Increased hydraulic pressure from the blood to the lumen
What type of medication may precipitate diarrhoea?
Oral antimicrobials
What is the normal thickness of the intestinal wall?
Less than 2mm
What are the principles of treatment for a horse with diarrhoea?
- Replace and maintain circulating volume 2. Replace lost electrolytes 3. Control endotoxaemia and sepsis 4. Binding of enterotoxins 5. Control secondary consequences 6. Nutritional support to promote mucosal repair 7. Re-establish normal GIT flora
What are maintenance fluid volumes for an adult horse vs. a foal?
Adult: 60ml/kg/day Foal: 100ml/kg/day
What factors do you need to consider when calculating fluid therapy volume?
Replacing the deficit, supplying maintenance and accounting for on-going losses
What is important to remember about the composition of replacement fluids?
Must be LOW potassium so they can be administered rapidly
When must you not give synthetic colloids?
In a coagulopathy as they will interefere with platelet ability to adhere to damaged blood vessels and form a clot
What are indications for antimicrobial use in horses?
- Systemically sick horse (fever, depression) 2. Immunocompromised (foal
What products can be used to bind toxins in the GIT?
Activated charcoal, Bio-sponge (di-tri-octahedral-smectite)
What are secondary consequences of diarrhoea?
Laminitis, gastric ulceration, renal failure, DIC, bacteraemia/septicaemia
How is digital cryotherapy useful in a case of diarrhoea?
Helps protect against laminitis by preventing activation of matrix metalloproteinases that disrupt laminar attachment
List some infectious causes of diarrhoea in adult horses:
Salmonella, clostridium, lawsonia intracellularis, cyathostomes
What is a dietary cause of diarrhoea in adult horses?
Carbohydrate overload (grain overload, lush pasture)
Describe the pathogenocity of salmonella in regard to diarrhoea:
- Ability to invade cells 2. Ability to replicate intracellularly 3. Complete LPS coat 4. Excretes toxins leading to intestinal hypersecretion
What are the four clinical presentations of salmonellosis in horses?
- Abortion 2. Subclinical carrier 3. Mild clinical disease 4. Severe clinical disease
Which medium enhance the viability of salmonaella when culturing faeces?
Cary-Blair transport medium or selenite broth
How many faecal samples should you take for culture if you suspect salmonella and why?
At least 3-5 (5-10gram) samples at 12-24h intervals to enhance chances of isolating with intermittent shedding
Are antimicrobials useful in a case of salmonellosis?
Not really… There is evidence that antimicrobials do not actually shorten the course of disease or reduce faecal shedding. There are also many resistance patterns in salmonella which can change over the course of the disease.
Salmonella: gram negative or positive?
Gram negative
Clostridium: gram negative or positive?
Gram positive
What is the best protection against pathogenic organsims in the gut?
Healthy normal flora!
Which clostridium species is considered part of the normal flora?
Clostridium perfringens
