Page 850 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 825

VetBooks.ir Feed with a high fibre content may cause violent be secondary to another lesion, therefore surgical
Coastal Bermuda hay is often dry and fibrous.
intervention is common. At surgery, massaging the
peristalsis, resulting in extraction of water from
the mass of ingesta, thus creating a drier and firmer impaction may break it down without recourse to an
enterotomy.
mass. Tapeworms may be a risk factor because of the Intraluminal infusion of saline may be necessary in
oedema and ulceration created at their attachment some cases. If the condition is secondary to ileal inflam-
around the ileocaecal orifice, thereby disturbing the mation, hypertrophy or local dysfunction, an incom-
motility and lumen diameter. plete or complete jejunocaecostomy may be necessary.

Clinical presentation Prognosis
The impaction causes a simple mechanical obstruc- In general, the prognosis is fair to good and is better
tion and therefore the clinical signs are usually mild than with most other small-intestinal disorders. The
early in the condition. As ileal distension progresses shorter the duration before surgical intervention the
signs of pain increase, but these are not usually as better the prognosis. Postoperative ileus is common.
severe as those seen with surgical lesions and they
usually subside in 6–10 hours. The abdominal pain MECKEL’S DIVERTICULUM
then returns as gastric and orad small-intestinal dis-
tension increases. Gastric reflux may be present if the Definition/overview
condition has been present for a while. Borborygmi Meckel’s diverticulum is an embryonic remnant of
are usually decreased. The heart rate is variably the vitelline duct that results in the formation of a
elevated. Dehydration with secondary circulatory blind sac that communicates with the lumen of the
compromise eventually arises following sequestra- small intestine.
tion of fluid in the intestine and reduced oral intake.
Aetiology/pathophysiology
Differential diagnosis The diverticulum can become impacted with
Because ileal impaction results in a simple obstruc- ingesta, resulting in chronic colic. If the impaction
tion, the main differential diagnoses are adynamic is severe necrosis can occur, followed by peritonitis.
ileus and DPJ. In more advanced cases, obstructive Inflammation of the diverticulum may also produce
small-intestinal conditions must be considered. adhesions to other loops of intestine. Wrapping of
the diverticulum around adjacent or other loops of
Diagnosis small intestine, thus causing strangulation, is pos-
Small-intestinal distension is usually palpable p/r. sible. Persistent vitelloumbilical bands may act as an
In approximately 25% of cases the impaction is pal- axis for small-intestinal volvulus.
pable on the midline medial to the caecum. Gastric
reflux may be present depending on the chronicity. Clinical presentation
Abdominocentesis usually yields normal fluid unless Clinical signs are most commonly seen in adult
intestinal compromise has developed from chronic horses. Signs are usually non-specific if luminal
and/or severe intestinal distension, when the protein obstruction is not present, and may be intermittent
level usually increases. A long-standing impaction and chronic. In these cases, intermittent signs of
may result in local necrosis and peritonitis. abdominal discomfort with possible periods of inap-
petence are reported. Clinical signs are severe if a
Management strangulation or volvulus occurs. Meckel’s diverticu-
Supportive medical therapy consisting mainly of i/v lum can also be identified as an incidental finding on
fluid therapy and analgesics may be successful in exploratory laparotomy or necropsy.
early cases. Intermittent gastric decompression may
be required, and a NG tube should be left in place or Differential diagnosis
passed regularly to detect and relieve gastric disten- A vast array of causes of chronic or acute colic should
sion. Diagnosis may be difficult and impaction may be considered.