Diarrhoea

Question 1

What is the average faecal output of a horse? When might this increase (non-pathologically)?

Answer 1

1kg every 2hrs (~12kg a day) May increase 20-28kg a day if fed grass hay / oats

Question 2

What are the 5 basic mechanisms of diarrhoea?

Answer 2

1. Malabsorption 2. Increased secretion 3. Decreased transit time (abnormal motility) 4. Osmotic overload 5. Increased hydraulic pressure from the blood to the lumen

Question 3

What type of medication may precipitate diarrhoea?

Answer 3

Oral antimicrobials

Question 4

What is the normal thickness of the intestinal wall?

Answer 4

Less than 2mm

Question 5

What are the principles of treatment for a horse with diarrhoea?

Answer 5

1. 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

Question 6

What are maintenance fluid volumes for an adult horse vs. a foal?

Answer 6

Adult: 60ml/kg/day Foal: 100ml/kg/day

Question 7

What factors do you need to consider when calculating fluid therapy volume?

Answer 7

Replacing the deficit, supplying maintenance and accounting for on-going losses

Question 8

What is important to remember about the composition of replacement fluids?

Answer 8

Must be LOW potassium so they can be administered rapidly

Question 9

When must you not give synthetic colloids?

Answer 9

In a coagulopathy as they will interefere with platelet ability to adhere to damaged blood vessels and form a clot

Question 10

What are indications for antimicrobial use in horses?

Answer 10

1. Systemically sick horse (fever, depression) 2. Immunocompromised (foal

Question 11

What products can be used to bind toxins in the GIT?

Answer 11

Activated charcoal, Bio-sponge (di-tri-octahedral-smectite)

Question 12

What are secondary consequences of diarrhoea?

Answer 12

Laminitis, gastric ulceration, renal failure, DIC, bacteraemia/septicaemia

Question 13

How is digital cryotherapy useful in a case of diarrhoea?

Answer 13

Helps protect against laminitis by preventing activation of matrix metalloproteinases that disrupt laminar attachment

Question 14

List some infectious causes of diarrhoea in adult horses:

Answer 14

Salmonella, clostridium, lawsonia intracellularis, cyathostomes

Question 15

What is a dietary cause of diarrhoea in adult horses?

Answer 15

Carbohydrate overload (grain overload, lush pasture)

Question 16

Describe the pathogenocity of salmonella in regard to diarrhoea:

Answer 16

1. Ability to invade cells 2. Ability to replicate intracellularly 3. Complete LPS coat 4. Excretes toxins leading to intestinal hypersecretion

Question 17

What are the four clinical presentations of salmonellosis in horses?

Answer 17

1. Abortion 2. Subclinical carrier 3. Mild clinical disease 4. Severe clinical disease

Question 18

Which medium enhance the viability of salmonaella when culturing faeces?

Answer 18

Cary-Blair transport medium or selenite broth

Question 19

How many faecal samples should you take for culture if you suspect salmonella and why?

Answer 19

At least 3-5 (5-10gram) samples at 12-24h intervals to enhance chances of isolating with intermittent shedding

Question 20

Are antimicrobials useful in a case of salmonellosis?

Answer 20

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.

Question 21

Salmonella: gram negative or positive?

Answer 21

Gram negative

Question 22

Clostridium: gram negative or positive?

Answer 22

Gram positive

Question 23

What is the best protection against pathogenic organsims in the gut?

Answer 23

Healthy normal flora!

Question 24

Which clostridium species is considered part of the normal flora?

Answer 24

Clostridium perfringens

Question 25

How would you treat a case of clostridium perfringens?

Answer 25

Antibiotics are indicated: Metronidazole. Supportive therapy. Bio-sponge.

Question 26

What is the mortality rate of clostridium perfringens vs. clostridium difficile?

Answer 26

Clostridium perfringens: 54-100% despite aggressive treatment Clostridium difficile: 19-27%

Question 27

What type of diarrhoea would you see in a case of clostridium perfringens vs. clostridium difficile?

Answer 27

Clostridium perfringens: mild - severe haemorrhagic diarrhoea Clostridium difficile: Scant faeces, green-brown diarrhoea (rarely haemorrhagic)

Question 28

What are risk factors for cyathostomiasis?

Answer 28

Overstocking and use permanent horse pastures, poor anthelminthic protocol, season (winter / spring), immunecompromise

Question 29

How would you treat cyathostomiasis?

Answer 29

Standard supportive case for diarrhoea. Anthelminthics (moxidectin 0.4mg/kg PO once). Corticosteroids - prevent colonic inflammation (dexamethasone 0.05mg/kg IV/IM)

Question 30

What are the 5 mechanisms of weight loss?

Answer 30

1. Decreased intake 2. Maldigestion / Malabsorption 3. Inappropriate utilisaton of absorbed nutrients 4. Increased requirement for nutrients 5. Increased losses

Question 31

What is the percentage of water in normal equine faeces?

Answer 31

75%