Page 472 - The Veterinary Laboratory and Field Manual 3rd Edition

Common clinical problems 409

If the diarrhoea is mild and animals appear well 1 × 1 × 1 cm and should be fixed in ten times
it may not be necessary to take any samples their own volume of buffered 10% formalin in
unless faeces are required for parasitology. If sealed, labelled jars.
there are any dead animals present perform a While waiting for laboratory results, if the
necropsy (see Appendix 2 and Chapter 8) and diarrhoea is severe, it may be necessary to begin
submit a full necropsy report along with fresh supportive treatment for affected animals. If the
and fixed tissue samples. Include sections of animal(s) is(are) not showing other clinical signs
intestine, especially from the ileocaecal valve this may not be necessary but routine worm-
(to check for Mycobacterium avium paratuberculosis ing and a change of diet may help. If affected
in cattle), and make several smears of intestinal animals are dehydrated or have a high tempera-
mucus/contents on glass slides (to check for the ture it may be necessary for the veterinarian to
presence of protozoa). Collect and note the pres- provide fluid replacement therapy and, where
ence of any parasites seen in the intestine and indicated, to give an injectable broad-spectrum
stomach. Make sure that samples of liver, lung, antibiotic to prevent primary or secondary bac-
spleen, kidneys and heart are included. Sections terial infections. It is often advisable to isolate
for histology should measure approximately the affected animal(s) from healthy stock while

Table 10.3 Some causes of diarrhoea in horses.

Cause Clinical signs Age commonly affected
Salmonella sp. Acute, profuse, foul smelling watery diarrhoea, Foals
pyrexia, many individuals affected
Actinobacillus equi Acute diarrhoea Outbreaks in foals
Corynebacterium Sudden onset, +/- respiratory disease, dehydration, Young foals
equi death
Clostridial sp. Acute, profuse, watery diarrhoea Any age
Aspergillus Chronic diarrhoea Foals
fumigates
Rotavirus Acute, profuse watery diarrhoea Newborn foals
Helminths Acute, sub-acute or chronic associated with heavy Usually older foals
infections (may have hypotroteinuria)
Any of the above Acute/chronic diarrhoea Older debilitated horses
Toxins, antibiotics Individual animals affected, may develop watery Older horses
diarrhoea with dehydration and malabsorption
Nutritional Chronic cases may have bulky faeces or profuse Older horses associated
diarrhoea. May also have mild cases. with inappropriate diet
Foal heat diarrhoea Occurs in mares on heat (when suckling) Mares 7–120 days after
parturition
Enterotoxigenic Acute, profuse watery diarrhoea, dehydration and Newborn calves < 3 days
E.coli acidosis (common in colostrally deprived animals) old
Salmonella spp. Acute dysentery, fever and deaths occur All ages, outbreaks can
occur precipitated by
stress

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