Information section~

Advancement in veterinary medicine and nutrition as led to longer life expectancies in our animal population, and there are more geriatric cats than before. With that comes more potential health problems. The most common ones listed by veterinary surgeons include kidney disease, hyperthyroidism, neoplasia, dental disease, and diabetes mellitus (Boehringer Ingelheim 2007). However in a study, most owners list their common “old cat disease” differently, with arthritis as the top of the list, followed by kidney disease, deafness, blindness, hyperthyroidism (less prevalent in HK compared to UK), bronchitis, and dental disease.

Various studies have shown evidence of arthritis on x-rays in 90% of cats over 12 years old. The most clinically significant changes are those affecting the elbows, hips and/or stifles. Evidence of vertebral bony changes were also observed in the studies, but their clinical significance in unclear in cats.

As in dogs (where there have been more studies over this topic in this species), arthritis causes pain and discomfort, which reduces the quality of life. However, this condition in cats is often missed by owners / vets due to various reasons:

1) Cats usually show stiffness instead of limping as arthritic changes are typically slow developing and symmetrical on both sides

2) Cat’s relatively small size and their ability to redistribute other weight onto other limbs means the effects of arthrtis is much less obvious than in dogs

3) Cats are very good at hiding their symptoms, and often modify their lifestyles than showing obvious pain / discomfort. In the case of outdoor or indoor/outdoor cats (less common in HK), cats suffering from arthritis may simply choose to go out less.

4) Cats are rarely taken out for walks by owners, and many owners do not take notice of their cat’s walking / running in the house.

5) Clinical signs of OA in cats are different and more subtle compared to humans and dogs (see below)

6) Affected joints may show some thickening (easily missed on physical exam). Reduced range of motion or increased fluid swelling is less common, and crepitus / clicking noises is rarely detected in cat. Therefore, OA is frequently missed by vets.

Pathogenesis:

Unfortunately, this is poorly understood in cats. Potential causes include previous trauma or infection, obesity, genetics, and idiopathic (unknown cause). Idiopathic is believed to be the cause of arthritis in 70-90% of feline cases. Underlying developmental defects appears to be less important in cats compared to dogs, where problems such as kneecap problems (medial patellar luxation) in small breeds and hip problems (dysplasia) in large breeds are common.

On the other hand, some feline breeds are indeed predisposed to problems such as hip and kneecap problems, often seen concurrently, which can lead to secondary OA. Hip problem is more commonly seen in Himalayan, Persian, Maine Coon, Devon Rex, Bengal and Abyssinian cats. Kneecap problem is more commonly seen in Abyssinian, Devon Rex, Bengal and Maine Coon cats. Both either of these conditions may also occur in other breeds.

Clinical Signs:

The most common clinical signs of arthritis in cats are often non-specific and vague, and could easily be caused by other common diseases. These are often attributed by owners / vets as “normal aging changes” and their significance is dismissed:

- weight loss - depression / signs of withdrawal (ie. increase hiding)

- reduced playing - increased time resting / sleeping

- abnormal toileting behaviour

- decreased grooming

- aggression

- reduced ability / hesitation to jump

- changes / decrease in the wearing of nails

- stiff gait (one of the most obvious signs but not easily noticed)

- pain when lifted up / reluctance to use cat flap

Diagnosis:

Confirmation of arthritis requires x-rays, but clinical signs may not correlate well with changes seen, especially in early disease. Also, sedation is often required which may be detrimental to the elderly cat.

Changes on x-rays can include new bone formation, bone remodeling, joint space narrowing, sclerosis, soft tissue swelling / thickening around joint, and increased joint fluid swelling.

As clinical signs are often vague and non-specific, and clients may not wish to pursue x-rays, vets are encouraged to spend more time in history-taking and to ask more searching questions. A questionnaire regarding the cat’s behaviour and motility is often useful while the owner is in the waiting room.

Investigations must be carried out to rule out other common diseases such as kidney disease, liver disease, gastrointestinal disease, diabetes, hypertension (high blood pressure) and hyperthyroidism. A thorough physical exam and blood pressure measurement should be performed, as well as an in-practice mobility assessment if possible. Blood work including FeLV/FIV test if appropriate. Urine analysis is also recommended.

Management:

Although arthritis is not easily diagnosed in cats and the clinical sings are less obvious than in dogs, it is wrong to assume cats suffer from less pain and discomfort and leave them un-treated.

Environmental Changes:

There are many little changes that owners can make to improve the lives of arthritic cats. However, changes should be made gradually as sudden changes in environment can lead to stress which can affects cats negatively:

- moving food / water bowls to a lower surface ; or raising them a little for cats with arthritic neck / front legs

- add ramps for easier access to favourite sleeping / hiding areas

- deep, padded comfortable bedding

- shallow-sided litter boxes

- sandy-type cat litter – which is often more comfortable on cats’ paws (individual cats may not like this litter and owners should observe for changes in urination)

Owners should always be aware of the five keys elements that cats need: food, water, litter box, resting places, and hiding places. Providing easier access to these would help arthritic cats cope better with their physical disabilities.

Weight Loss:

Reduced weight in obese / overweight cats decreases the load on joints as well as joint inflammation. However, any weight loss program should aim at gradual weight loss as cats are prone to liver problems (fatty liver).

Dietary Modification:

There are many supplemented diets on the market for arthritic dogs and cats. Studies have shown positive effects of diets supplemented with ingredients such omega-3 fatty acids (ie. Hill’s Canine j/d?) in arthritic dogs. Hill’s Feline j/d? - which is supplemented with antioxidants, essential fatty acids, and ingredients which also aids in protecting joints and obesity management - is actually designed for cats with arthritis, and has been shown to improve cognitive function and mobility in >70% and >50% cats respectively.

(For information on Cognitive Dysfunction Syndrome in cats, please refer to a separate article)

Glucosamine, chondroitin supplements, extract of tumeric and green-lipped mussel:

There are no published studies on the efficacy of these supplements in arthritic cats. While they may be beneficial, they will only provide partial relief in early and mild cases, and are unlikely to have much effect in severe cases.

Non-steroidal anti-inflammatory drugs (NSAIDs):

This is often the first-line treatment for osteoarthritis in many species. Studies have show moderate or marked improvements in 75% cats with arthritis that were given meloxicam, one of the commonly used NSAIDS in cats. Improvements include willingness to jump, height of jump, reduced joint pain on palpation, and improved temperament.

However, since care must be taken as NSAIDs are potentially be harmful to the kidneys and gut, especially in cats. Kidney function should be assessed before and during treatment, and the lowest possible dose should be used. NSAIDs should be avoided in animals with dehydration, poor circulatory / liver / kidney / gut / clotting function, and those receiving steroids or diuretics.

Glucocorticoids:

Despite their anti-inflammatory properties, their usefulness has not been reported in arthritic cat. Experience in other species suggests limited use in this arthritis. They also have potentially detrimental effects on cartilage and other organ systems.

Other treatment modalities:

1) Pain Relief

2) Surgery – not often used except for kneecap and hip problems or severe joint disability, and often considered as a last-resort.

3) Other Interventions (ie. acupuncture, physiotherapy, massage) – they may be beneficial in individual cases

Summary:

It is important to recognize and treat arthritis in cats as it can significantly improve the welfare and quality of life of our feline patients. Thorough investigation should be carried out and treatment should be individualised for each patient.

Main source of references from Prof. Danielle Gunn-Moore, Professor of Feline Medicine in The University of Edinburgh