Approach to equine diarrhoea Flashcards

1
Q

Diarrhoea

A

faecal material with increased water content/increased volume/increased frequency

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2
Q

Pathophysiology of equine diarrhoea

A

Malabsorption surface epithelium
§ Atrophied villi
§ Disrupted sodium and chloride transport (water should flow in with Na and Cl)

Hypersecretion crypt epithelium
§ Inflammatory mediators and bacterial toxins -> endothelial injury loss of villi -> increased crypt epithelium surface area
§ Activation of cellular pathways -> water, chloride, sodium secretion

Hypermotility
§ Reduced transit time, stimulated by inflammation

Osmotic
§ Incomplete digestion of carbohydrates -> increased osmotic pressure in lumen

Endothelial dysfunction: increased hydrostatic pressure
§ Fluid from vasculature -> interstitium -> lumen

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3
Q

Clinical signs of equine diarrhoea

A

Pyrexia

Depression

Inappetence

Tachycardia

Tachypnea

Colic

…many present similarly regardless of causes

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4
Q

Viral causes of equine diarrhoea

A

Coronavirus

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5
Q

Bacterial causes of equine diarrhoea

A

Salmonella
Clostridia
Neorickettsia (Potomac horse fever)
(Lawsonia)

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6
Q

Parasitic causes of equine diarrhoea

A

Cyathostominosis

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7
Q

Iatrogenic causes of equine diarrhoea

A

NSAIDs
Antimicrobials

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8
Q

Dietary causes of equine diarrhoea

A

Diet change
Grain overload
Sand

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9
Q

Inflammatory causes of equine diarrhoea

A

Granulomatous
Eosinophilic
Lymphocytic/plasmacytic

Lymphoma

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10
Q

Non-GI, non-infectious causes of equine diarrhoea

A

Peritonitis
Liver disease

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11
Q

Toxic causes of equine diarrhoea

A

Acorns
Arsenic
Cantharadin

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12
Q

Equine coronavirus

A

Betacoronavirus, emerging pathogen

Apparently low fatality rate

Pyrexia of unknown origin, lethargy, anorexia

Diarrhoea, leukopaenia, colic

Diagnosis
○ Faecal PCR (transport on ice)
○ Population shedding low, +ve test likely to be relevant

Treatment/management
○ Supportive/symptomatic
○ Shedding for 2-5 weeks

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13
Q

Equine salmonellosis

A

Zoonotic

S. enterica (typhimurium, agona)

Faecal-oral transmission

Intracellular (enterocytes)
○ Evades the immune system

Host susceptibility increased by stress
○ Hospitalisation
○ General anaesthesia
○ Antimicrobial administration

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14
Q

Presentations of equine salmonellosis

A

Other than diarrhoea, salmonella is also associated with increased incidence of small colon impactions

Variable presentations
○ Severe acute colitis (classic)
○ Pyrexia, tachycardia, neutropaenia but no diarrhoea
○ Asymptomatic shedding

If they survive, may have chronic diarrhoea and protein loss

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15
Q

Diagnosis of equine salmonellosis

A

Faecal culture 30-50% sensitivity

PCR 98-100% sensitive

Five daily faecal samples

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16
Q

Treatment of equine salmonellosis

A

Supportive

Antimicrobials may not alter course of disease
§ Not a benign intervention

If chronic diarrhoea >4-5 weeks prognosis is poor

17
Q

Equine Clostridia

A

Clostridium difficile, Clostridium perfringens

Gram +ve anaerobes

Zoonotic

Also identified in healthy horses
○ Toxin production important

Antimicrobial administration/nosocomial infection

Usually acute
○ May be found dead
○ Similar to other causes of enterocolitis

Diagnosis
○ Clostridial toxin ELISAs
§ C. difficile toxins A and B
§ C. perfringens enterotoxin/beta toxin

Treatment
○ Symptomatic
○ Metronidazole
§ Oral/per rectum if cannot tolerate
§ Appetite suppressant

18
Q

Potomac horse fever

A

Neorickettsia risticii

Severe, very watery diarrhoea

Severe laminitis common

Treatment: oxytetracycline

19
Q

Lawsonia

A

Obligate intracellular Gram -ve bacteria

Causes proliferation of crypt epithelial cells in the intestine (ileum initially)

Affects foals 2-13 mo (peaks 4-7mo)

But documented to affect horses up to 17yo – very rare

20
Q

NSAID induced equine diarrhoea

A

Two manifestations
○ Right dorsal colitis
○ Generalised NSAID toxicity

Ulcerated mucosa, protein losing enteropathy

Anorexia, lethargy, fever, endotoxaemia, hypoalbuminaemia

Often inappropriate dosing - not always

Treatment
○ Symptomatic
○ Misoprostol
§ Synthetic prostaglandin analogue
○ Sucralfate

21
Q

Antimicrobial induced equine diarrhoea

A

Some geographic element
○ Different antimicrobials/different regions

Association with C. perfringens, C. difficile, and S. enterica

Do not chop and change antimicrobials
○ Broader spectrum bigger effect on flora

Macrolides
○ Motilin receptor agonist as well as antimicrobial
○ Do not give to animals >5mo

22
Q

Carbohydrate overload induced equine diarrhoea

A

Small intestine digestion overwhelmed -> large intestine

Rapid fermentation gram +ve lactic acid producing bacteria
○ ↓↓ pH
○ Lactic acid poorly absorbed = ↑ osmotic load

Death of gut microbial population -> endotoxin release

If severe -> mucosal ulceration

Laminitis

23
Q

Viral causes of diarrhoea in foals

A

Rotavirus
Adenovirus
Coronavirus

24
Q

Bacterial causes of diarrhoea in foals

A

Salmonellosis
Clostridiosis
Rhodococcus equi (1-4mo)
Lawsonia (weanling)

25
Q

Septic causes of diarrhoea in foals

A

Associated with FPT

26
Q

Parasitic causes of diarrhoea in foals

A

Strongyloides westeri
Cryptosporidium

27
Q

Non infectious causes of foal diarrhoea

A

Foal heat diarrhoea (7-14 days)

Antibiotic associated

Lactose intolerance

Sand

Gastric ulceration

28
Q

Chronic diarrhoea in horses

A

Longer then 7-14 days

29
Q

Possible causes of equine chronic diarrhoea

A

Dietary

Sand enteropathy

Inflammatory bowel disease

NSAIDs

Peritonitis

Chronic infectious causes (e.g. cyathostominosis, salmonellosis)

30
Q

Treatment of chronic diarrhoea in horses

A

Intravenous fluid therapy
§ Crystalloids
§ Plasma/synthetic colloids

Monitor electrolyte status
§ Hypochloraemia
§ Hyponatraemia
§ Hypokalaemia
§ Hypocalcaemia

Metabolic acidosis
§ Hypoperfusion of tissues -> anaerobic respiration -> lactic acid
§ Reduced bicarbonate
§ Less able to correct imbalances (underperfused kidneys)

Analgesia

Antimicrobials?
§ Neutrophils <1 x 109 ?

Anti-endotoxin?
§ Polymyxin B
§ Flunixin is not anti-endotoxic

Transfaunation?

Prevent secondary complications
§ Laminitis
§ Thrombophlebitis

Adsorbents
§ Di-tri-octahedral smectite: ‘Biosponge’
§ Binds bacterial toxins
§ Oral administration

Psyllium
§ SCFAs e.g. butyrate à energy for enterocytes
§ Cheap and easy!

Diet
§ Short fibre length/low bulk
§ Feed buffets