August 09, 2018

NY Vet 2017: Osteoarthritis in Cats

Diagnosing joint disease in feline patients can be difficult, but recognizing and managing this chronic, painful condition is important for achieving optimal quality of life.
By Laurie Anne Walden, DVM, ELS

Adequately managing osteoarthritis (OA) in cats vastly improves their quality of life, said Susan Little, DVM, DABVP, at the 2017 New York Vet conference in New York City. In her presentation, Dr. Little discussed the prevalence of OA in cats, the challenges of diagnosing feline OA, as well as various treatment options.

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OA in cats is underdiagnosed, said Dr. Little, co-owner of 2 feline practices in Ottawa, Canada. “[Cats are] often really good at masking their signs of orthopedic disease,” she noted. In addition, the disease is often bilateral, so gait abnormalities are harder to spot than they are with unilateral disease. Understanding these barriers to symptom recognition is a step toward making the diagnosis, she said. In cats, OA is more likely to be primary (idiopathic) than secondary. OA in dogs is more often secondary to hip dysplasia, trauma, or another cause. For veterinarians, this means that feline patients can have OA with no history of a predisposing condition.
 

Prevalence

The risk of OA “dramatically increases with age in cats,” Dr. Little said. Most senior cats have OA, she added. She recommended that veterinarians assume all cats over about 10 years of age have OA unless proved otherwise. The most common OA locations in cats are the elbow, knee, and hip. Some cats have lumbosacral OA accompanied by spondylosis. Dr. Little noted that arthritis in this location can cause signs similar to those of ataxia. Cats sometimes present for neurologic workup when the real problem is spinal arthritis, she said. She suggested keeping this in mind when presented with an older cat with ataxia but no other signs of neurologic disease.
 

Diagnosis

The first step in diagnosis, Dr. Little said, is having an “index of suspicion that your patients are likely to have OA.” She described a diagnostic triad of physical examination, radiography, and owner observations to help practitioners confirm the suspected diagnosis.

No specific diagnostic test exists for some feline medical conditions, she added. In these cases, a therapeutic trial can be part of the diagnostic process. “[OA] is one of the diseases in cats where response to treatment is a perfectly valid diagnostic tool,” she said.

Physical Examination
Dr. Little begins an examination of an older cat by gently palpating the entire body to locate sites of pain and then examining those areas last. “A good physical exam tip...especially with senior cats,” she said, “is to leave the difficult stuff, the painful stuff, maybe the stuff the cat doesn’t like...until the end.”

Localizing pain in cats is challenging. Dr. Little discussed several clues that a cat may be experiencing joint pain. Muscle atrophy from limb disuse can indicate chronic pain. Overgrown claws can be a sign of decreased mobility. Cats with arthritis may have unkempt fur because they do not feel well enough to groom or cannot groom themselves without pain. Cats may also overgroom painful areas, she said, suggesting that practitioners pay attention to bald spots over elbows or other joints. She also mentioned that a bald spot on the ventral abdomen of a cat with an otherwise normal coat can be a sign of bladder pain from idiopathic cystitis.

Cats with OA tend to develop joint pain and swelling. They are less likely to develop joint effusion, restricted range of motion, and crepitus, which are typical signs of OA in dogs.

Gait assessment is not always possible with cats, Dr. Little noted. She reminded the audience not to exclude OA from the differential diagnosis if a cat does not cooperate with an attempt to evaluate its gait.

Radiography
“Normal radiographs do not necessarily rule out OA in the cat,” Dr. Little said. “The problem is that cats... just have less radiographically evident pathology than dogs do.” Study results have shown that cats with OA are more likely to have cartilage changes than bone changes, she said.

Owner Observations
“We rely a lot on getting information from owners,” Dr. Little remarked. “Owners may notice changes in their senior cat. Whether they’ll report them to you is another matter.” Cat owners may think that arthritis signs are normal aging changes. She recommended asking owners specific questions about behavioral and physical changes and discussed tools that veterinarians and owners can use to uncover signs that a cat is experiencing chronic pain.

Videos and photographs of cats at home can yield important clues, she said. Videos of a cat grooming, getting in and out of the litter box, ascending and descending stairs, and jumping on and off furniture can be helpful. She also asks owners for photographs of cats resting. She pointed out that most cats at rest tuck in their forelimbs. A cat that consistently holds a forelimb in extension could be compensating for elbow pain, she said.

Dr. Little recommended giving owners a specific screening tool: the Feline Musculoskeletal Pain Index. This instrument was developed by the Comparative Pain Research Laboratory at the North Carolina State University College of Veterinary Medicine.1 It is a 17-item questionnaire in which cat owners rate their pet’s ability to perform various activities, such as jumping onto the kitchen counter, climbing stairs, stretching, grooming, interacting with family members, and using the litter box. The tool includes instructions for scoring the responses. Dr. Little suggested having owners complete the questionnaire at home, ideally before the appointment, so they will have time to think through the responses. “The worst time to ask an owner to fill out a questionnaire is...when they’re in your clinic,” she said.

Dr. Little also recommended a brochure published by the American Association of Feline Practitioners that helps owners recognize signs of pain in cats.2 The brochure describes behavioral changes that can indicate pain (such as hiding and becoming aggressive) and the importance of monitoring cats’ responses to therapy for chronic pain.

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