Page 882 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 857

VetBooks.ir bypass or resection and anastomosis, and long-term Based on one retrospective study of 22 cases, horses
with segmental eosinophilic colitis treated surgi-
postoperative antimicrobial administration.
Prognosis cally had a good prognosis for survival. Horses with
abdominal abscesses that require treatment in addi-
The prognosis for intestinal neoplasia is guarded tion to long-term antimicrobial administration also
to poor as the tumour may extend to other organs. have a poor to guarded prognosis.

DISORDERS OF THE SMALL COLON AND RECTUM

SMALL-COLON IMPACTION faecal output. As the condition progresses, they
develop abdominal distension and exhibit moderate
Definition/overview to severe signs of abdominal pain. NG reflux is an
Impaction is the most common disorder of the small inconsistent finding.
colon. This portion of the intestine seems to be
predisposed to impaction as the lumen of the large Differential diagnosis
colon narrows acutely through the transverse colon Differential diagnoses for this condition include any
into the small colon. Ponies, American miniature intraluminal obstruction of the large intestine in
horses and Arabian horses appear to develop small- horses. This includes large-colon and caecal impac-
colon impactions more frequently than other breeds. tions and foreign-body, enterolith and faecalith
obstructions.
Aetiology/pathophysiology
The aetiology of small-colon impaction includes Diagnosis
ingestion of poor-quality roughage, poor denti- Diagnosis of impaction of the small colon is based
tion, parasitism, dehydration and motility disorders. on the observation of clinical signs and rectal palpa-
Older horses seem to be more frequently affected tion. By the time horses with impaction of the small
than younger horses, probably due to deterio- colon are presented to a veterinarian, they usually
rated dentition and decreased small colon motility. have decreased faecal production and a distended
Small-colon impactions occur more frequently dur- abdomen and exhibit moderate to severe signs of
ing the autumn and winter, as access to water may colic. On rectal examination, one or several firm,
be decreased and consumption of coarse roughage tubular and digesta-filled loops of small colon can
material is increased. be palpated. The thickness of the wall and palpa-
Impaction causes an intraluminal obstruction of tion of a single, free tenial band help identify the
the small colon and, as a result, ingesta, fluid and gas small colon.
accumulate in segments of the GI tract proximal to
the impaction. Horses with small-colon impaction Management
deteriorate slowly because of the aboral location of Medical conservative management is often suc-
the small colon and the large space for the ingesta, cessful in the treatment of horses with mild to
fluid and gas to accumulate orad to the impaction. moderate impactions. Aggressive enteral and/or
As the impaction persists, the intestinal segments parenteral fluid therapy is used to overhydrate the
proximal to the obstruction, mainly large colon and horse, stimulate intestinal secretion production
caecum, become more and more distended and the and break the impaction down. Analgesics are used
affected horse experiences colic. to control abdominal pain and exercise is used to
stimulate intestinal motility. Administration of
Clinical presentation an enema in standing horses is not recommended
Horses with impaction of the small colon present unless the impaction is located in the distal portion
initially with only mild signs of colic and reduced of the small colon near the rectum and the horse