Page 866 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 841

VetBooks.ir completely isolated from other animals. If this is not 4.165
feasible, they should be separated as much as possi-
ble from other horses, particularly neonates. Barrier
precautions, including overboots, gloves and either
disposable gowns or dedicated coveralls, should be
used. Medical instruments (e.g. thermometers, NG
tubes) and other items (buckets, shovels, wheelbar-
rows) should be used only for affected horses or com-
pletely disinfected after each use. The area outside
the stall should be cordoned off and disinfected fre- Fig. 4.165 Infarction of the large colon in a
quently. Horses with colitis should not be allowed on 6-month-old foal with colitis secondary to DIC.
common pasture.
SAND ENTEROPATHY
Prognosis
The prognosis is variable and should be considered Definition/overview
fair in horses with severe, acute colitis. Death can Sand enteropathy is an uncommon but regionally
occur as a result of severe toxaemia, necrotising important cause of diarrhoea.
enterocolitis, intestinal rupture, intestinal infarction
from DIC, laminitis or, in some cases, because of the Aetiology/pathophysiology
high cost of treatment. Infarction of intestinal blood Accumulation of sand in the large colon is usu-
vessels, likely as a result of severe toxaemia and DIC, ally associated with sand impaction; however, sand
can account for sudden deterioration (Fig. 4.165). enteropathy can also result. Sand may be ingested
Laminitis and catheter-site complications may occur while grazing on sandy soil or from ingestion of
in up to 25% of severe cases. If a horse recovers, sand in sandy paddocks, arenas or stalls. Horses that
long-term GI complications are uncommon; how- are underfed or kept in overstocked, closely grazed
ever, it may take weeks to months to return to nor- pastures may be at greater risk. Sand enteropathy is
mal body condition. more common in areas with loose sandy soil.
With salmonellosis, horses that recover may shed It is believed that sand accumulation can result in
Salmonella for weeks to months following resolution chronic irritation of the colonic mucosa. This may
of clinical signs. Three to five negative faecal cul- result in reduction of the absorptive surface area and
tures should be obtained before the horse is consid- interference with normal intestinal motility, result-
ered to no longer be infectious. ing in diarrhoea.
Vaccination for PHF appears to reduce the
severity of disease. Vaccines for the prevention of Clinical presentation
C. perfringens-associated disease are available for Diarrhoea is the main presenting sign. Diarrhoea
ruminants. While there are anecdotal reports of may be acute or chronic. Diarrhoea is usually
administering these products to horses, particu- mild and not associated with severe dehydration,
larly to mares for the prevention of neonatal diar- toxaemia or cardiovascular compromise. Pyrexia,
rhoea, this is not recommended because of limited anorexia, weight loss and intermittent colic may be
evidence of efficacy and an apparent high incidence present. ‘Sand sounds’ may be heard over the ven-
of adverse vaccine reactions. Judicious use of antimi- tral abdomen. Colonic rupture secondary to severe
crobials, particularly those that tend to be associated inflammation and irritation is rare but will result in
with a higher incidence of diarrhoea, is important. the development of septic peritonitis.
Antimicrobials that have not been shown to be safe
in horses should be avoided. Differential diagnosis
In general, the prognosis for PHF is good if diag- Infectious causes of colitis, including Salmonella,
nosed early and appropriate therapy is started. The C. difficile, C. perfringens and N. risticii (PHF), should
prognosis is worse if laminitis develops. be considered.