How is arthritis best diagnosed in cats?
The diagnostic approach to arthritis in cats is similar to that in dogs, though it generally seems incomplete and less exact
and rarely leads to a specific diagnosis. When obtaining a history in an older cat, tailor your questions to focus on notable
changes in behavior or activity, rather than asking if the cat has exhibited lameness.
Gait observation in cats is rarely helpful. An orthopedic examination focusing on detecting joint changes requires that we
know what a normal joint feels like in cats.5 No data have been published regarding normal ranges of motion in cats. Because of a cat's small size and thick fur and skin,
it is difficult to detect small changes indicative of joint distention or periarticular fibrosis.
Identifying the painful joint requires a somewhat relaxed patient until we manipulate that site. Many cats are not that cooperative.
And then, once you've found one painful site, they become resistant to further manipulation. Of course, if you suspect a painful
area, leave that area to last. Many cats are sensitive to spinal manipulation, but we don't know if we can attribute this
to degenerative processes in the vertebral column. Similarly, cats may exhibit tail sensitivity, but we cannot say with certainty
that it indicates lumbosacral disease. It is important to perform a complete examination for possible neurologic or systemic
conditions that might mimic arthritic signs. Sedation is often necessary to complete the examination, particularly if joint
instability is suspected.
Because physical examination findings can be difficult to interpret, radiography may help localize the problem.8 But keep in mind that radiographic findings can be misleading. In our analysis of arthritis in older cats, we specifically
reviewed the radiographs of cats without a history of lameness.1 Since it was a retrospective radiologic study, we did not know whether the cats had behavioral, gait, or physical examination
changes that coincided with the radiographic changes, but it does suggest that marked radiographic abnormalities do not necessarily
correlate with clinically identifiable disease. Synovial osteochondromatosis is a good example of a pathologic process that
has impressive radiologic findings,8 but the condition may or may not be associated with clinical joint disease. Conversely, cats with nonerosive immune-mediated
diseases may exhibit pain because of acute joint inflammation but have few radiographic changes.
Hip dysplasia can cause severe hip degeneration in cats and is diagnosed similarly to how it is diagnosed in dogs. However,
it is often an incidental finding. Young cats in the acute stage may present with lameness, but it usually resolves with conservative
management (e.g. activity limitations, diet restrictions, supplements, possibly nonsteroidal anti-inflammatory drugs [NSAIDs]). However, a
femoral head ostectomy may be indicated in cats with severe coxofemoral joint laxity and pain.
Lumbosacral degeneration can cause marked clinical signs in cats. Cats may no longer jump or seek affection. Sensitivity to
stroking in the caudal lumbar region or tail manipulation may be noticed. Radiographic evidence of lumbosacral disease includes
narrowing, sclerosis, spondylosis, or abnormal motion of the lumbosacral space. Myelography, epidurography, computed tomography,
or magnetic resonance imaging may be needed to confirm the diagnosis.
Objective analysis of the gait in cats has been evaluated by using a force pad.9 This device records the weight placed on each paw as the animal walks across the pad. While a force pad is not likely to
be available for routine clinical use, it will be a useful tool for evaluating treatment effects (e.g. assessing response to NSAID therapy). At North Carolina State University College of Veterinary Medicine, Dr. Duncan Lascelles
has completed a similar study evaluating the gait of normal cats.10 He is also attempting to examine limb loading during landing from a jump and is comparing video-and harness-mounted motion
detectors as other methods to objectively analyze activity.
What is the best medical management approach for cats with signs of arthritis?
If a cat is overweight, diet restriction (i.e. changing feeding from ad lib to controlled amounts, eliminating or reducing high-calorie treats or table scraps) helps reduce
stress on the joints and, thus, makes the patient more comfortable. The environment of cats with arthritis can be restructured
to reduce the need for stressful activities such as jumping. However, as in dogs and people, it may be beneficial in cats
to encourage a little activity to keep the muscles and joints active. Creativity will be needed for these independent creatures.