Equine Diarrhoea Flashcards
How is the approach to equine diarrhoea different to that of small animals?
DON’T think of small vs large bowel.
Apart from foals - think of as a big dog!
What usually causes diarrhoea in horses?
usually GIT (occasionally other e.g. liver)
ADULT = LARGE INTESTINE foal = small or large
What is the function of the colon in horses?
Water reabsorption
Microbial digestion of carbohydrate and protein/non-protein nitrogen —— VFA production
How can you narrow down the differentials for equine diarrhoea?
Age of animal
Duration of clinical signs
History - presence of risk factors
What are the ddx for neonatal foals with diarrhoea?
Foal heat diarrhoea
Viral - especially rotavirus
Salmonella
Clostridium
Less likely: Necrotising enterocolitis Sepsis Nutritional diarrhoea Parasitic diarrhoea - strongyloides westeri Gastroduodenal ulceration
How likely is it that a foal will get rotavirus?
DEPENDS ON AGE
Likely in young foals, less likely in older foals up to 10-12 months
What are the ddx for older foals (up to 10-12 months) with diarrhoea ?
Parasitic diarrhoea - Strongylus vulgaris, cyathostomins
Proliferation enteropathy - Lawsonia intracellularis
Salmonella
Clostridia
Less likely:
Cryptosporidiosis, Rhodococcus equi, Viral, Sepsis, Nutritional, Gastroduodenal ulcer, Parasitic diarrhoea - strongyloides westeri
What are the ddx for a horse with diarrhoea?
Salmonellosis
Clostridiosis
Idiopathic acute colitis
Less likely: Parasitism - cyathostominosis, strongylosis Antimicrobial associated NSAID toxicity (right dorsal colitis) Sand enteropathy Carb overload, IBD, Dietary, Neoplasia.
What is the typical treatment approach to diarrhoea in horses?
Treat symptomatically
Why is it important to differentiate between acute and chronic diarrhoea?
Acute = EMERGENCY in adult horse
Chronic can go on for months
How does acute diarrhoea present?
Acute onset febrile (with fever) diarrhoea
Clinical signs of hypovolaemia and endotoxaemia
How would you define chronic diarrhoea?
Diarrhoea of more than two weeks duration
Otherwise healthy animal
What can cause both acute and chronic diarrhoea in adult horses?
Salmonellosis
Parasitism - Strongylus vulgaris, larval Cyathastominosis
Sand enteropathy
NSAID toxicity (right dorsal colitis)
What can only cause acute diarrhoea in adult horses?
Clostridiosis
Antimicrobial associated diarrhoea
Carbohydrate overload
What can only cause chronic diarrhoea in adult horses?
Inflammatory or infiltrative disorders e.g. IBD
Dietary - abnormal fermentation
Neoplasia - Lymphoma
Peritonitis, abdominal abscessation
What risk factors should be considered to narrow down the ddx list?
Treatment with NSAIDS
Anthelmintic history
Antibiotic treatment
Contact with other horses/foals with diarrhoea
Why should you try to make a definitive diagnosis?
To make sure it isn’t contagious or a zoonosis
Some conditions need specific treatments e.g. Psyllium for sand colitis
What are the three key principles of therapy in horses with diarrhoea?
Address fluid loss
Address inflammation and endotoxaemia
Address specific cause
If you can see a skin tent on a horse, what is its percentage dehydration?
At least 5%
Could be more if there are more clinical signs
What is the maintenance volume of fluid for a horse?
2-4 ml per kg per hour (about 48L)
How do you calculate the amount of fluid required?
Deficits - e.g. 5% dehydrated - need to add 5% back
Maintenance - 2-4 ml /kg / hr
Ongoing losses- diarrhoea quantity
What is endotoxin?
LPS molecule part of the outer cell wall of gram negative bacteria
Systemic response to endotoxin causes pathology
SIRS-MODS-Death
What do sirs and mods stand for?
Systemic inflammatory response syndrome
Multiple organ dysfunction syndrome
How does endotoxin enter the horse’s blood?
Horse gut normally has large number of G-ve bacteria in lumen (for fermentation and digestion)
Normal mucosal barrier prevents access to circulation - if this barrier is broken down = ENDOTOXAEMIA
Once endotoxin is in the circulation, how does it progress?
Endotoxin interacts with cells e..g macrophages and inflammatory mediators released (e.g. IL-1,6, TNF)
Initiates SIRS
Clinical signs of endotoxaemia
CV and GI dysfunction, shock, MODS, DIC, DEATH
What are the clinical signs associated with endotoxaemia?
Depression, Tachycardia, Tachypnoea, Fever - endotoxin = pyrogen Colic Diarrhoea Hyperaemic ‘toxic’ mucous membranes
Why is tachypnoea associated with endotoxaemia?
Vasoconstriction results in decreased absorption of oxygen
Therefore resp rate increases
What cellular changes would you expect to see with endotoxaemia?
Low white cell count
Low neutrophil count
Immature ‘band’ neutrophils
Why is neutropenia associated with endotoxaemia?
Neutrophil margination
What are the treatment approaches for endotoxaemia ?
- Prevent movement of endotoxin into the circulation
- Neutralise endotoxin before it interacts with inflammatory cells
- Prevent synthesis, release or action of inflammatory mediators
- Prevent endotoxin-induced cellular activation
How can you prevent access of endotoxin into the circulation?
Surgically remove necrotic tissue in colicing horse
How can you neutralise endotoxin before it interacts with inflammatory cells?
Polymixin B - binds LPS
Hyper immune plasma - has antibodies against LPS
How can you prevent inflammatory cell activation?
Pentoxifylline
How can you inhibit SIRS?
Flunixin
What is a key difference between endotoxaemia in horses and foals?
In foals, usually associated with bacteraemia / sepsis
- treatment - concern with nephrotoxicity therefore no polymixin B or flunixin
- Treat with plasma and antibiotics
Why are horses likely to be hospitalised with ACUTE diarrhoea?
To keep up with fluid requirements
Chronic doesn’t need as much fluid
How is fluid managed in foals?
Volumes not as large as adult horses
Can give intermittent, frequent boluses, or separate mare and foal for continuous fluid
What management consideration needs to be made when hospitalising a foal?
BRING MOTHER
How could you assess whether a horse needs to be referred based on fluids?
In horse/foal can keep up with fluid requirements by drinking then probably can be treated at home
BE CAREFUL WITH FOALS - can deteriorate very rapidly
