Page 245 - Veterinary diagnostic imaging birds exotic pets wildlife

CHAPTER 21 III Guinea Pigs 241

in the same household. Guinea pigs are also subject to
attack by strange dogs and cats when taken outside the
home for a “walk.”
Guinea pigs are often injured accidentally by their
owners, sometimes quite seriously (Figure 21-15). In
addition to the usual extremital fractures, typically
caused by being stepped on or having a leg caught in
a closing door, guinea pigs are also subject to crush
injuries, particularly to the chest, and some of these
injuries can be extremely serious.

III DISEASES

In our practice, the two most common reasons for
obtaining a medical imaging consultation in a guinea
pig are suspected bloat and urinary tract calculi. Less
often, consultation for pneumonia, gastrointestinal

obstruction, or nonspecific abdominal masses is
sought. Most such examinations are predominantly
radiographic, although there are the occasional con-
trast studies and ultrasound examinations. I have yet
to identify extreme ovarian enlargement because of
cysts, but marked unilateral and bilateral enlargement
have been reported.
Guinea pigs also suffer from a wide variety of joint
diseases, many of which are symmetrical and result
in marked structural alteration to the affected joints.
For the most part these are predominantly generative
forms of arthritis (new bone deposited on preexist-
Figure 21-10 • Ventrodorsal projection of what at fi rst appears to ing bone), at least as viewed from a radiological
be a pair of skulls, one superimposed on the other. But closer perspective.
inspection reveals the “second skull” to be an extremely dense
mandible.
Bloated Stomach
The liver is the easiest solid abdominal organ to Bloat is a gaseous distention of some part of the gas-
identify, principally because of the contrasting lung trointestinal system (but most often the stomach) and
and stomach that lie on either side in the lateral view can have a variety of adverse effects including colic,
and cranially and caudally in the VD view. The kidneys obstruction, and dyspnea.
may or may not be identifi able, depending mainly on Colic often accompanies overdistention of the
the presence or absence of surrounding gas; this is also stomach or bowel secondary to inappropriate stimula-
true of the urinary bladder. tion of the autonomic nervous system. Marked gastro-
intestinal distention, particularly of the stomach, can
lead to secondary compression, kinking, or twisting of
Limbs
the cardia or pylorus, leading to obstruction.
The limbs of guinea pigs, like those of their relatives, Distention of the stomach, or cecum, places pressure
are small compared with the size of their trunks and on the diaphragm, making it physically more diffi cult
can be somewhat difficult to physically isolate when to breathe, as well as making it feel more diffi cult to

being imaged unless the animal is drugged or uncon- breathe. Gastric distention may also produce varying
scious and the legs are taped to the cassette. If manual amounts of regional venous compression, which causes
restraint is used, a tongue depressor, which is radio- anoxia of the stomach wall, predisposing to rupture if
graphically transparent, can be used to draw a pig’s not alleviated.
leg away from its body and held while being radio- Radiographically, a bloated stomach is usually
graphed (Figure 21-14). characterized by gaseous distention, typically in the
left cranial half of the abdomen. When air and gas
are present together, the stomach content appears a
III INJURIES medium rather than a dark shade of gray (Figure
21-16). In some instances, the stomach may become so
As with the other small cage pets seen in our hospital, large that it reaches caudally all the way to the pelvis
most of the injuries received by guinea pigs are the and can resemble cecal enlargement (Figure 21-17).
result of attacks by cats and dogs, which often reside Text continued on p. 248.

2/11/2008 11:09:42 AM
ch021-A02527.indd 241
ch021-A02527.indd 241 2/11/2008 11:09:42 AM