Page 868 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 843

VetBooks.ir Differential diagnosis a complete pelleted diet should be fed until resolu-
Long-stem roughage (hay) should be withheld and
For the acute form, salmonellosis, clostridial enteri-
tis, PHF, peritonitis, intestinal accident and sand
Pasture should be avoided. Affected horses should
enteropathy are the main differential diagnoses. tion of all clinical and haematological abnormalities.
For the chronic form, IBD, intestinal neoplasia, be fed small meals frequently. If body weight cannot
cyathostominosis, protein-losing nephropathy and be maintained, dietary fat should be increased via
Lawsonia intracellularis infection (weanlings) should addition of a high-fat concentrate diet or supplemen-
be considered. tation with corn oil (250 ml q12 h). It has been sug-
gested that addition of psyllium (50–100 g/500 kg/
Diagnosis day, divided into 1–4 doses) could be useful because
Right dorsal colitis can only be definitively it is hydrolysed to short-chain fatty acids, which are
diagnosed via surgical biopsies or necropsy. an important energy source for colonic enterocytes.
Clinically, right dorsal colitis is a presumptive Surgical intervention, often involving colon resec-
diagnosis. A complete blood cell count and serum tion, may be indicated in severe, acute presentations
biochemical profile should be submitted, with or refractory chronic cases.
hypoproteinaemia being the main abnormality.
A thickened right dorsal colon may be observed Prognosis
ultrasonographically; however, this may be dif- Overall, the prognosis is guarded, although in some
ficult to identify. Urinalysis should be performed cases cessation of NSAID therapy and basic sup-
to rule out renal protein loss. Abdominocentesis portive care is all that is required. The prognosis
should be performed to identify other causes of for return to normality is better in horses with acute
disease. A presumptive diagnosis is usually made disease and when NSAID cessation is possible. The
in horses with appropriate clinical signs, severe prognosis is poor in horses with severe, chronic
hypoproteinaemia, exclusion of other causes and a hypoproteinaemia. Serial monitoring of blood albu-
history of NSAID administration. min levels, with gradual but steady elevation in albu-
min, is a good prognostic indicator. Full recovery
Management may take months. Laminitis is a possible complica-
NSAID administration should be ceased if possible. tion, particularly in acute cases.
If analgesia is required, alternative options such as
transdermal fentanyl, epidural opioids, intravenous CYATHOSTOMINOSIS
CRI lidocaine or ketamine or parenteral opioids
should be considered. Definition/overview
In horses with acute disease, intravenous fluid Small strongyles (cyathostomes) are important GI
therapy with a balanced electrolyte solution is often parasites worldwide. Small-strongyle infection can
required. Aggressive fluid therapy should be avoided cause a range of signs including inapparent infec-
if possible, particularly in hypoproteinaemic ani- tion, ill-thrift and severe protein-losing enteropathy
mals. With chronic disease, fluid therapy is usually and diarrhoea (larval cyathostominosis). In some
not indicated. areas (e.g. the UK), larval cyathostominosis is con-
In horses with acute or chronic disease, trans- sidered to be the most common cause of diarrhoea in
fusion of plasma or synthetic colloids is required adult horses.
in severely hypoproteinaemic animals. Sucralfate
(20–40 mg/kg p/o q6 h) may be useful, although it is Aetiology/pathophysiology
unclear whether significant drug levels are achieved The small-strongyle group consists of approximately
in the right dorsal colon. Administration of the syn- 50 different species. There are some differences in
thetic prostaglandin misoprostol (5 µg/kg p/o q12 h) prevalence, pathogenicity and life cycle between
has been used; however, its effect is not known, and some of these species; however, speciation is rarely
adverse effects can be encountered. performed. Multiple species are often present.