Page 256 - Veterinary diagnostic imaging birds exotic pets wildlife

252 SECTION II III The Mammals

Figure 21-22 • Veterinarian closely observes guinea pig
that has been described as being lame by its owner.

dislocation, they usually produce little more than a some respects resembles the radiographic appearance

nonspecific localized or regional swelling. In the case of chondromatosis that often affects the stifles of older
of a moderate (second-degree) or severe (third-degree) cats.
sprain, it may be possible to palpate a dislocation, but
this usually requires a strong analgesic or sedative to Infection
examine the animal humanely.
I have identified by ultrasound an intramuscular Hematogenous infections, most of which are pre-

hematoma causing a compartment syndrome in a sumed, typically occur in immature and young adult
young puppy that had sustained a severe crush injury. guinea pigs, usually in the peripheral appendicular
This injury is yet another means by which a non– joints. Less frequently, infections, including abscesses,
weight-bearing lameness might occur in a traumatized occur in the cranial mediastinum, lung, peritoneal
guinea pig and then identified without radiographic cavity, and individual organs, including the liver and

evidence of injury. stomach.
Although these infections begin by causing one or
more swollen joints (in the case of skeletal lesions) and
Osteoarthritis
thus can be recognized radiographically as being
Traumatic Osteoarthritis. Osteoarthritis in guinea intraarticular, they soon spill into the extraarticular
pigs, or any of the small mammalian cage pets, is often tissues, masking the initial nidus. Because the perios-
the result of a previous injury, particularly articular teum covering the tarsal (and carpal) bones is the rela-
fractures and serious sprain injuries that are associated tively primitive fibrous type, it is slow to react; for

with dislocation. Proximal femoral growth plate frac- example, it takes a month or more in most in-
tures are notorious in this regard, with some chronic stances, unlike the periosteum covering the long bones,
injuries so radically changing the appearance of the which typically responds in a few days after being
joint that it becomes nearly unrecognizable (Figure stimulated.
21-23). Thus, if interior bone destruction is seen, especially
when accompanied by one or more widened cartilage
Nontraumatic Osteoarthritis. Guinea pigs can also spaces, the infection probably did not begin recently
develop osteoarthritis for which there is no obvious (Figure 21-26). An exception to this is some types of
explanation. The stifle seems particularly prone to this penetrating wound in which the bone or joint has been

type of disease (Figures 21-24 and 21-25), which in inoculated directly by one or more bacteria.

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