Diarrhoea in Horses and Foals Flashcards
How does the function of the colon in foals differ to that of adult horses? In this case, how does the pathophysiology of diarrhoea in these age groups differ?
Foals have a less well developed colon as they gain nutrition from milk. Therefore most of their nutrient and fluid absorption occurs in the small intestine.
Horses - LI problems result in diarrhoea
Foals - SI mainly but also LI
How is the differential list narrowed down in equids?
AGE of animal
Duration of signs - less helpful
History/risk factors
What are the most common causes of diarrhoea in neonatal foals, and which are not exclusive to this age group(indicated by *)?
Foal heat diarrhoea
Viral (rotavirus - generally <6mo)
Salmonella*
Clostridia*
What are older foals more likely to be affected by?
Parasites
Proliferative enteropathy
(Infection by Lawsonia intracellularis which invades enterocytes and causes hyperplasia of immature crypt cells so malabsorption ensues)
How likely is diagnosis of a specific condition in horses?
Unlikely - most cases of diarrhoea go undiagnosed.
What questions need to be asked at history taking to narrow down the differential list for equine diarrhoea? Think about risk factors.
NSAIDs
Regular anthelmintics (may want to include management and whether anthelmintics are swapped frequently)
Antibiotic treatment
Other animal contact
Why might a specific diagnosis be useful?
Incase the cause is infectious or zoonotic or whether there is a specific treatment available.
What are the principles of therapy for diarrhoea?
Address fluid loss, inflammation/endotoxaemia, address the specific cause.
What needs to be included when assessing how much fluids to replace?
Replace losses
Maintain
Ongoing losses
When will a horse suffer from endotoxaemia?
When the normal mucosal barrier breaks down.
How does endotoxin lead to its clinical signs?
Endotoxin interacts with cells e.g. macrophages. This initiates systemic inflammation which can lead to CV and GI dysfunction, shock and organ failure and death.
What are the clinical signs of endotoxaemia?
Depression, tachycardia, tachypnoea, fever, colic, diarrhoea, hyperaemic ‘toxic’ MMs.
What is seen on a leukocyte profile of a horse with endotoxaemia?
Low WBCs, neutrophils and increased band neutrophils
What are the principles of endotoxaemia treatment?
Prevent access to circulation (surgery)
Neutralise endotoxin
Prevent synthesis/release of inflammatory mediators
Prevent endotoxin induced cellular activation
Which drugs are available in the UK that can treat endotoxaemia and what do they do?
Polymixin B - directly binds endotoxin
Pentoxifylline - prevents cellular release of inflammatory mediators (but not that effective)
Flunixin - an NSAID so prevents PG synthesis.
