Page 859 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

834 CHAPTER 4

VetBooks.ir is a poor response to medical therapy or when be evident and an area of resonant tympany is usu-
Surgery is typically recommended when there
ally present over the right flank. Borborygmi may
there is significant caecal distension or abdomi-
nal pain. The potential for caecal rupture exists be decreased on the right side. Abdominal distension
may be evident. Signs of toxaemia or cardiovascular
even with apparently small impactions, and some compromise should not be present with primary cae-
authors recommend early surgical intervention. cal tympany. Tachypnoea may be present if there is
Typhlotomy is usually performed to remove the significant abdominal distension and pressure on the
impaction. thoracic cavity.

Prognosis Differential diagnosis
Most caecal impactions resolve with medical ther- Other causes of colic, particularly those resulting
apy, but some may require prolonged treatment. in gaseous distension of the large colon, should be
Caecal rupture is a major concern and can occur considered.
without warning. It should be suspected in any horse
with caecal impaction that deteriorates suddenly Diagnosis
and carries a grave prognosis. Recurrence of caecal Diagnosis is based on p/r detection of a large, gas-
impaction is common in some animals. Presumably distended caecum in the right side of the abdomen. If
this is because of underlying problems in intestinal marked distension is present, the base of the caecum
motility, intestinal-wall damage from the initial may protrude into the pelvic canal and it is some-
impaction or the continued presence of predisposing times difficult to differentiate caecum from large
factors. Surgical bypass may be indicated in recur- colon. Other diagnostic tests are unlikely to differ-
rent cases. entiate the caecum from the large colon.

CAECAL TYMPANY Management
The approach to caecal tympany depends on the
Definition/overview severity of signs and whether primary or second-
Gaseous distension of the caecum, otherwise known ary tympany is present. For secondary tympany, the
as caecal tympany, is a cause of colic. inciting cause must be addressed. Most cases of pri-
mary caecal tympany will respond to withholding
Aetiology/pathophysiology of feed, walking and analgesics. Analgesic therapy is
Primary and secondary caecal tympany may occur. described earlier.
Primary caecal tympany occurs in the absence of Fluid therapy is indicated in dehydrated horses
an outflow obstruction and arises via excessive gas and may be useful in all cases. If marked caecal
production in the caecum and/or a reduction in cae- distension is present, either with primary or sec-
cal motility. Dietary changes, lush pasture and high- ondary tympany, caecal trocharisation may be
grain diets may be predisposing factors. Secondary required (Fig. 4.159 and Table 4.9). Caecal rupture
caecal tympany occurs as a result of a caecal outflow is a concern, mainly with severe and/or chronic
obstruction (e.g. large-colon displacement, impac- distension. Exploratory coeliotomy and caecal
tion or volvulus). decompression or typhlotomy may be required.
Very rarely will typhlectomy be indicated. This
Clinical presentation should be reserved for severe, recurrent primary
Non-specific signs of colic of varying severity will be caecal tympany where management changes have
evident. Heart rate will be elevated consistent with had no effect.
the degree of pain. Very high heart rates and severe Management (particularly diet) should be evalu-
pain can be present with severe tympany or as a ated. Access to lush pasture should be restricted,
result of an underlying process such as a large-colon high-grain diets should be avoided and dietary
volvulus. Bloating of the right paralumbar fossa may changes should be made gradually.