EQUINE CLINICAL PATHOLOGY - Rossdale & Partners

G u i d e t o e q u i n e c l i n i c a l p a t h o l o g y
Peritoneal fluid
Analysis of peritoneal fluid is particularly
useful as a diagnostic aid in cases of colic,
weight loss and other suspected abdominal
disease. It may be of particular value in
helping to make the decision for surgical
intervention.
To perform a peritoneal tap, the skin over
the site of puncture should be clipped
and prepared as for surgical intervention.
With the horse restrained in the standing
position, a 19 gauge, 1.5 or 2.0 inch
needle or following local anaesthesia and a
stab incision, a 7.5 cm. blunt teat cannula
(operator preference) is carefully advanced
through the skin at the lowest part of the
abdomen and then through the linea alba.
If fluid is not immediately forthcoming, the
needle may be rotated or the tap may be
repeated at other sites.
In foals, prior ultrasound scan examination
of the abdomen is recommended to
help visualise abnormalities and prevent
inadvertent penetration of the intestine.
Examination of the ventral midline will help
to locate the spleen and to find a ‘pocket’ of
peritoneal fluid to guide productive needle
puncture. Similarly, if fluid is not obtained
in adult horses using the blind technique
described above, ultrasonic guidance may
be helpful.
A turbid and homogeneously blood stained
sample may indicate abdominal vascular
embarrassment. A white, turbid fluid may
suggest peritonitis. A brown, foul smelling
fluid may indicate intestinal rupture or an
intestinal tap. A thick and heavily blood
stained sample suggests a splenic tap.
Total nucleated cell counts