Diarrhoea in horses and foals Flashcards Preview

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Flashcards in Diarrhoea in horses and foals Deck (21):
1

Function of colon - adults and foals

ADULT: water reabsorption and microbial digestion (carbohydrate and protein/non-protein nitrogen)
FOAL: large colon not as well developed as in adults so bacterial pipulation less and less important for fluid absorption. Milk diet.

2

Where is the problem causing diarrhoea located in adults vs foals?

Adult - LI only
Foal - LI or SI

3

How to narrow down the list of DDx for equine diarrhoea - 3

-Age of animal?
-Duration of clinical signs?
-History - presence of risk factors?

4

DDx - neonates - commonest (4) and others (5)

COMMONEST: foal heat diarrhoea, viral (esp rotavirus), salmonella, clostridia
OTHERS: necrotising enterocolitis, sepsis, nutritional diarrhoea, parasitic diarrhoea (Strongyloides westeri), gastroduodenal ulceration.

5

DDx - older foals (up to 10-12 months) - commonest (4) and others (7)

COMMONEST: parasitic (strongyloides vulgaris, cyathostomins), proliferative enteropathy (Lawsonia intracellularis), Salmonella, Clostridia

OTHERS: crytosporidiosis, Rhodococcus equi colotis, viral (especially rotavirus), sepsis, nutritional diarrhoea, gastroduodenal ulceration, parasitic (Strongyloides westeri)

6

What is foal heat diarrhoea?

Nothing to do with the mare's first heat cycle after parturition but an adaptation/change of the foal's bacterial population in GIT.

7

DDx - adult equine diarrhoea - common (3) and others (9)

COMMON: Salmonellosis and clostridiosis, or often undiagnosed
OTHERS: parasite, antimicrobial-associated, NSAID, sand enteropathy, carbohydrate overload, inflammatory or infiltrative, dietary (abnormal fementation) neoplasia (lymphoma), peritonitis, abdominal absecessation

8

Differentiate acute and chronic diarrhoea

-ACUTE - acute onset, febrile diarrhoea, clinical signs of hypovolaemia, endotoxaemia
-CHRONIC: if more than 2 weeks duration
-The DDx for acute and chronic actually overlap quite a lot (e.g. salmonellosis, parasitism (larval cyathostominosis, strongylosis), NDSAID toxicity, sand enteropathy and carbohydrate overload can all be either acute or chronic).

9

What are 'risk factors' for equine diarrhoea - 4

-NSAID treatment
-anthelmintic history?
-antibiotic treatment?
-contact with other horses/foals with diarrhoea?

10

Is it important to make a definitive diagnosis?

Probably not but you should try because:
-contagious +/- zoonosis
-some specific treatments may work better

n.b. always test an equine diarrhoea case for salmonella

11

3 principles of therapy = ?

-address fluid loss
-address inflammation and endotoxaemia
-address specific cause

12

Principles of fluid therapy?

Mild dehydration seen with 5% fluid loss, sever dehydration with 10% fluid loss. For a 500kg racehorse, figures can be the following:
-deficits - 50L
-maintenance - 48L (2-4ml/kg/hr)
-ongoing losses - 50L
TOTAL = 150L. I/V fluids for this can cost £750 a day!

13

What is an endotoxin?

Part of OM of gram - bacteria. Released during cell death or rapid growth. Horse FIT normally has large numbers of gram negative bacteria but the normal mucosal barrier prevents access to circulation. Endotoxaemia is a complicating factor in many GIT diseases.

14

Why worry about endotoxaemia?

Endotoxin within circulation --> interacts with cells (e.g. macrophages) --> initiates systemic inflammation --> clinical signs of endotoxaemia --> CV and GIT dysfunction, shock, organ failure and death

15

Clinical signs - endotoxaemia - 7

-depression
-tachycardia
-tachypnoea
-fever
-colic
-diarrhoea
-hyperaemic 'toxic' mucous membranes

16

Diagnosis - endotoxaemia

Clinical signs
Low WBC count, low neutrophil count, immature 'band' neutrophils

17

Treatment - endotoxaemia

-prevent movement of endotoxin into the circulation (hard to do)
-neutralise endotoxin before it interacts with inflammatory cells
-prevent synthesis/release/action of inflammatory cells
-Prevent endotoxin-induced cellular activation

18

What drugs can be used in endotoxaemia? 4

Polymixin b (directly binds endotoxin)
Pentoxyfilline - less effective than polymixin b
Flunixin - blocks prostaglandin production
Hyperimmune plasma (USA) - neutralises endotoxin

19

How is endotoxaemia different in foals? - 4

Similar effects as in adult horses but usually associated with bacteriaemia/sepsis (unlike adults).
-Large colon less well developed therefore gram negative population may be smaller?
-Concern of nephrotoxicity (foal kidney less well developed) of certain drugs (polymixin B or flunixin)
-Treatments = plasma or ABs

20

Can you treat diarrhoea at home or do you need to refer? 4

-Most diagnostic tests/treatments don't require hospitalisation
-Keeping up with fluids may be challenging (volume and frequency required). If a horse/foal can keep up with fluid requirements by drinking then it is probably okay to treat at home.
-best to be over cautious with foals as they can deteriorate very rapidly
-consider possibility of contagious agent? other animals nearby? (isolation facilities can be provided at a hospital)

21

Considerations - foals on fluids

-volumes required aren't as large a adults so may be possible to give intermittent but frequent boluses OR
- separate mare and foal for continuous fluids but this is labour intesive!