Arthritis and degenerative joint disease in cats 
It is well recognised that as humans get older they are likely to suffer from joint pain caused by osteoarthritis. It is also well known that older dogs commonly suffer from arthritis and both owners and vets are familiar with the medication dispensed to relieve their pain.
However until relatively recently, arthritis in cats was not commonly diagnosed or treated. This may be due in part to the cats’ survival instinct to hide signs of pain, and the lack of recognition of the condition by owners and veterinary surgeons
Prevalence of arthritis in cats
Due to the challenges of diagnosing arthritis in cats, it can be difficult to tell how many cats are affected. However, recent studies looking at radiographs of older cats produced startling results. In one study published in 2002, 90% of cats over 12 years of age had evidence of degenerative joint disease. This included cats with so-called ‘spondylosis’ of the spine (a form of degenerative joint disease). However, even when these cases were excluded, around 2/3 of the cats still had radiographic signs of arthritis affecting the limb joints. More recent studies have shown radiographic evidence of arthritis in the limb joints affecting between 60% and more than 90% of cats. All these studies show that arthritis is actually very common in cats, that it is much more common (and more severe) in older cats, and that the shoulders, hips, elbows, knees (stifles) and ankles (tarsi) are the most commonly affected joints.
What causes arthritis in cats?
Osteoarthritis is a complicated type of arthritis in which the normal cartilage that cushions the joint degenerates and is worn away, resulting in inflammation, discomfort, ongoing damage and secondary changes in and around the joint. OA can be primary (without an obvious underlying cause, where the disease may arise at least in part due to mechanical ‘wear and tear’ in the joints) or secondary to a joint injury or abnormality as described below. The other major form of arthritis seen in humans is rheumatoid arthritis, which is (at least in part) an auto-immune disease.
At present it is not entirely clear what causes arthritis in cats. Further studies are needed to determine if this is similar to osteoarthritis in humans, where mechanical damage to the joints may be pivotal in development of the disease, or whether other factors are involved. At present, most cats with arthritis do not appear to have an obvious predisposing cause.
Some factors may increase the risk of arthritis in cats:
- Genetics – certain breeds have an increased risk due to various underlying joint problems. This would include:
• Hip dysplasia (abnormal development of the hip joints) seen especially in Maine Coon  cats (but also Persians , Siamese  and other breeds)
• Patella luxation (dislocation of the knee cap) which has been reported more commonly in Abyssinian  and Devon Rex  cats
• Scottish Folds  are particularly prone to severe arthritis affecting multiple joints due to an abnormality of cartilage that occurs in the breed
- Injury or trauma – for examples fractures, dislocations and other joint injuries. These may cause abnormal joint conformation which can result in secondary osteoarthritis
- Obesity  – there is no evidence that this causes arthritis, but it is likely to make an existing condition worse
- Acromegaly – this is an unusual condition of older cats where a tumor in the pituitary gland secretes too much growth hormone. Affected cats usually develop diabetes mellitus , but some also develop secondary arthritis in their joints.
What are the signs of arthritis in cats?
Cats are masters of hiding discomfort and pain, so often do not demonstrate obvious signs that you might expect. They restrict their own activity to minimise the use of the sore joints and so tend not to show the same signs of arthritis as other animals. In particular, cats uncommonly show overt signs of limping or pain associated with arthritis. Major signs of arthritis in cats associated with arthritis are:
• Reluctance, hesitance or refusal to jump up or down
• Jumping up to lower surfaces than previously
• Jumping up or down less frequently
• Difficulty going up or down stairs
• Stiffness in the legs, especially after sleeping or resting for a while; occasionally there may be obvious lameness
• Difficulty using the litter tray
• Difficulty getting in our our of the cat flap
• Increased time spent resting or sleeping
• Not hunting or exploring the outdoor environment as frequently
• Sleeping in different, easier to access sites
• Reduced interaction and playing less with people or other animals
• Reduced frequency or time spent grooming
• Matted and scurfy coat
• Sometimes overgrooming of painful joints
• Overgrown claws due to lack of activity and reduced sharpening of claws
• More irritable or grumpy when handled or stroked
• More irritable or grumpy on contact with other animals
• Spending more time alone
• Avoiding intact with people and/or animals
How is arthritis diagnosed in cats?
As arthritis is more common and more severe in older cats, it should be looked for in any mature (7 years plus) or older cat. A diagnosis is often based primarily on the presence of appropriate signs and chances in the home environment (see above). If you see any of these changes, it is important to have your cat checked by your vet as arthritis is an uncomfortable and painful condition.
When your vet examines your cat, they may be able to detect pain, discomfort, swelling or other changes affecting certain joints. If there is any uncertainty, your vet may suggest taking X-rays of the joints, but this is not always needed, and in some cases if the diagnosis is uncertain a simple trail treatment (with anti-inflammatory drugs) may be used.
Although further investigations such as blood and urine tests are note usually needed to investigate arthritis, your vet may suggest these if they think there may be another problem as well (which is not uncommon in older cats), or prior to starting some medications.
Managing arthritis in cats
Many options should be considered when managing a cat with arthritis, and it is not just about finding the right tablet to control the disease!