Equine Diarrhoea Flashcards
Are equine diarrhoeas usually 1* or 2* GIT?
1*
Occasionally 2*
What is the funtion of the colon in horses? Foal?
- Water reabsorption
- microbial digestion of carbohydrate and protein/nonprotein nitrogen
> less well developed in foals due to milk diet (digested by SI)
Which section of GIT is diarrhoea in the adult most common? In the foal?
LI
In foals may be SI or LI
What 3 stages of questioning help narrow down the DDx list?
- Age of animal?
- Duration of clinical signs?
- History - presence of risk factors [drugs, other animals affected]?
Give 8 DDx for neonatal foal diarrhoea
1- Foal heat diarrhoea 2- Viral (esp. rotavirus) 3- Salmonella and clostridia [can occour at ANY age] 4- Netcrotizing enterocolitis 5- Sepsis 6- Nutritional diarrhoea 7- Parasitic diarrhoea (strongyloides westeri) 8- Gastroduodenal ulceration
Define the age of a Neonate
< 2 weeks
What is foal heat diarrhoea cause by? Where did the name originate?
- change in gut flora between 1-2weeks of age
- foal is NOT SICK, just has diarrhoea
- coincides with mares first oestrus cycle post partum
Give 10 DDx for older foals (10-12 months)
1-Cryptosporidiosis
2-Parasitic: Strongyloides Vulgaris [->colic], Cyathostominosis
3-Proliferative enteropathy: Lawsonia Intracellularis
4-Rhodococcus equi colitis
5-Viral (rotavirus) - less likely in older foals
6-Salmonella and clostridia
7-Sepsis
8-Nutiritonal
9-Gastroduodenal ulceration
10-Parasitic - S Westeri
Give 10 DDx for adult horses
1- Salmonellosis and clostridiosis
2- Parasitism (larval cyasthostominosis, strongylosis)
3- antimicrobial-associated
4- NSAID toxicity (right dorsal colitis)
5- Sand enteropathy
6- Carbohydrate overload
7-IBD (or other inflammatory or infiltrative disorders)
8- Dietary - abnormal fermentation
9- Neoplasia (10yrs+) - lymphoma, peritonitis and abdominal abscessation
10- UNDIAGNOSED!
What are the 2 categories when describing the duration of clinical signs?
> Acute: Acute onset febrile diarrhoea, animal sick, clinical signs of hypovolaemia, endotoxaemia, fever, often blood diarrhoea
Chronic: Diarrhoea for >2 weeks but usually still eating/drinking etc.
Give 2 causes of diarrhoea which cause acute clinical signs ONLY
- Clostridiosis
- Antimicrobial-associated diarrhoea
Give 2 causes of diarrhoea which cause chronic clinical signs ONLY
- Inflam/infiltrative disorders (IBD)
- Neoplasia (Lymphoma, peritonitis, abdominal abscessation)
Give 4 potential “risk factors” to help narrow down the differential list
- treatment with NSAIDs [ask specifically, owners may forget flunixin/bute is a drug if been given long term! -> right dorsal colitis]
- Anthelmintics [be aware resistance; insistent cyathostomins emerge in spring -> mechanical damage to GIT]
- Antibiotics [Clostridium]
- Contact with other horses/foals with diarrhoea and their ages
Is it important to make a definitive diagnosis?
Probably not
- but you should try because could be contagious/zoonotic (eg. salmonella)
- specific treatments useful
What are the 3 principles of diarrhoea therapy in horses?
- Address fluid loss
- Address inflamation and endotoxaemia
- Address specific cause
How are fluid therapy dose rates calculated?
- Deficits (ie. % dehydrated; estimated by poor jugular fill, skin tent, sunken eyes etc. meaning 5%, anything above this = more so)
- Maintenance (2-4ml/kg/hr)
- Ongoing losses (estimate, can be <100l/day)
What is the average weight of a horse? Foal?
500kg
50kg
What is endotoxin? When may it cause a problem?
- Part of the outer membrane of gram -ve bacteria, normally present in gut due to commensal gut flora (fermentation and digestion of cellulose)
- Released during cell death
- Normal mucosal barrier prevents access to circulation
> mucosal barrier breakdown -> endotoxaemia
Why is endotoxaemia a particular problem in horses?
Have a very low tolerance of endotoxin cf. other species.
- endotoxin in circulation interacts with cells (eg. macrophages)
- Initiates systemic inflammation
- clinical signs of endotoxaemia = depression, tachycardia, tackpnoea, fever, colic, diarrhoea, hyperaemic toxic membranes
- CV and GI dysfunction, shock, organ failure, death
How is the diagnosis of endotoxaemia confirmed?
- clinical signs
- usually LOW white cell count (as all migrated to infectino site)
- LOW neutrophil count
- Immature band neutrophils
> Endotoxin assay possible but low sensitivity and takes a long time to complete
What 4 ways may endotoxaemia be treated?
1 - prevent movement of endotoxin -> circulation
2 - neutralise it before it interacts with inflammatory cells
3 - prevent synthesis, release or activation of inflammatory mediators
4 - prevent endo-toxin induced cellular activity
How can you prevent movement of endotoxin -> circulation?
Remove sections of necrotic gut
How may endotoxin be neutralised to prevent it interacting with inflammatory cells?
- Polymixin B
- Hyperimmune plasma (USA only)
- Pentoxyfilline
- Flunixin
How can you prevent the synthesis, release or activation of inflammatory mediators?
- Pentoxyfylline prevents release of inflammatory mediators from cells (IL1, TNF, IL6 etc.)
- Flunixin blocks PG production [may cause GIT problems so use with care!]
