Your cat may have arthritis.
Osteoarthritis in cats is similar to that in people and dogs. OA, also referred to as degenerative joint disease, is where cartilage is worn down and / or damaged, and possible new bone formation develops around bony joints. This results in varying degrees of pain and swelling, leading to low grade inflammation and reduced range of motion. Simply put, it is uncomfortable and your cat knows it. Cats can develop OA in all joints, but it is most pronounced in the knee, elbow, and hip joints. OA is not limited to these joints, it can occur in the spine as well.
Cats are enigmatic and generally do not express their discomfort to us humans. Or so we think. Many signs of OA in cats are simply brushed off as the cat being older or learning not to jump onto a particular piece of furniture. We also may think that cats are simply being lazy – not unheard of – but more likely than not, there’s underlying joint inflammation and arthritis. Older cats that become less active generally have arthritis.
The most common clinical signs reported by cat owners include hesitation or reluctance to jump up or down, hesitation to climb up or down stairs, decreased grooming, difficulty walking, behavior changes (seeking more solitude, or becoming aggressive), and inappropriate litter box habits. Rarely do cats vocalize that they are in pain. It is inappropriate to think that just because a cat is not vocalizing pain that it is not uncomfortable! In addition about 1/3 of all cats with OA are more sensitive to being touched or picked up. Cats with OA are also less likely to groom; they simply cannot bend without pain, so they don’t.
Not addressing a cat’s underlying arthritis, aside from knowing that the cat is uncomfortable may lead to further lack of activity and muscle mass loss, exacerbating the OA. When activity decreases cognitive decline may occur and this can impact the relationship that a person has with their cat. OA is a serious quality of life issue that frequently is not addressed.
Diagnosis is made via history, physical examination, and frequently X-rays of affected joints. Not every cat will have visible abnormalities on X-rays, and in other cases, the X-rays may show severe signs, but the cat is not synchronous with the X-ray findings. History and physical exam are essential as is the response to treatment in confirming the diagnosis.
Treatment ideally involves a multimodal approach. For quite some time veterinarians have used a glucosamine / chondroitin sulfate supplement to aid in arthritis treatment, along with pain medications, such as gabapentin and non-steroidal anti-inflammatories. Adequan, a joint fluid precursor, given at home via injection, can help slow and mildly reverse OA in certain cases., is also frequently used. None of these supplements or medications are approved and labeled by the FDA for use in felines.
Recently a new medication has been approved for use in cats to control the pain and lower inflammation associated with OA in cats. Solensia, a monoclonal antibody given via injection once per month, greatly reduces the pain of OA. It works via binding to a molecule called nerve growth factor (NGF), a signaling protein that is produced by injured tissues. NGF binds to receptors on nerves, making them more sensitive to pain, and it causes other cells in the body to release pro-inflammatory factors, leading to more NGF production.
Monoclonal antibodies function similarly to natural antibodies in a cat’s body: they bind to a specific molecule, rendering that chemical unable to perform its function. Solensia binds to NGF, neutralizing it, while not affecting any other molecules or signaling mechanisms within the body. It has been shown that targeting NGF is effective at significantly decreasing OA pain while avoiding unintended effects. By decreasing the sensitivity to pain, the cat is more comfortable. The Solensia-NGF protein is then broken down and eliminated by the body with no ill effects.
The medication is given monthly via injection at the veterinary hospital. Clinical effects may be seen in as little as a few days, but it is advised to not assess the full benefit until after several doses. In addition to the once monthly dosing and efficacy in over 77% of cats receiving Solensia, it is safe to give to cats with kidney and liver disease.
Solensia may be an important new tool to help control pain from arthritis in cats. It can be used with other modes of OA control, such as glucosamine / chondroitin supplementation and Adequan, as appropriate.
Older cats that appear to be slowing down or “learning” to not jump on the counter may be painful and have arthritis. We now have a new tool to return their mobility and comfort. Please ask one of our veterinarians if you have concerns that your cat has arthritis – we may be able to help.
Dan Teich, DVM
District Veterinary Hospitals