Page 897 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

872 CHAPTER 4

VetBooks.ir abate. Fever and depression may be present initially, ultrasonographically (Fig. 4.187). Abdominocentesis
is invaluable and should be performed in horses with
but the condition typically progresses rapidly as septic
shock develops. Body temperature may be elevated,
With peritonitis, abdominal fluid may range from
normal or decreased. Heart rate is almost invariably colic and an unexplained fever to rule out peritonitis.
elevated and can be very high (>100 bpm). Respiratory serosanguineous and turbid to brownish with the
rate is usually elevated. Mucous membranes progress presence of ingesta. Typically, marked increases in
from normal to hyperaemic to cyanotic. GI sounds cell count (15–800 × 10 /l) with degenerative changes
9
decrease, and dehydration develops as fluid is seques- in neutrophils and an increased total protein level
tered in the abdomen. A variable degree of colic are present. Intracellular bacteria are often evident
may be evident. Sweating and anxiety are common. cytologically. Bacterial culture of abdominal fluid is
Horses with idiopathic primary peritonitis typically particularly useful if a ruptured abdominal abscess
have milder clinical signs consistent with non-specific is suspected. Occasionally, normal abdominal fluid
colic, although fever is not uncommon. is obtained because of pocketing of fluid, particularly
early in the disease, so abdominocentesis should be
Differential diagnosis repeated in a horse with suspected septic peritonitis,
Colitis, pleuritis, strangulating intestinal lesions and but a normal initial tap, if clinical signs progress.
other causes of sepsis or endotoxaemia may appear Idiopathic primary peritonitis typically results
similar. in less marked haematological changes. Abdominal
fluid varies from mild changes to markedly increased
Diagnosis nucleated cell counts and protein. Accumulation of
With severe contamination neutropenia with toxic large amounts of free fluid is rare in idiopathic pri-
changes in neutrophils is almost always present but mary peritonitis.
is non-specific. Total protein levels tend to decrease
rapidly and haematological changes consistent with Management
dehydration and metabolic acidosis may be present. The prognosis for severe septic peritonitis is grave
Occasionally, the intestinal viscera will feel ‘gritty’ and consideration should be given to whether an
p/r. Sometimes, the abdomen will feel abnormally attempt at treatment is justified. The inciting cause
empty following intestinal rupture. A large volume must be identified and addressed whenever possible.
of hyperechoic abdominal fluid is usually evident Exploratory laparotomy is often indicated (Fig. 4.188).

4.187 4.188

Fig. 4.187 Excessive hyperechoic free abdominal Fig. 4.188 Distended small intestine (white arrows)
fluid (arrowed) is evident in this horse with septic and caecum (black arrow) with patches of fibrin (red
peritonitis. arrows) in a horse with septic peritonitis.