Joint Cartilage Erosion in Cats

Age and overall health are main factors in the development of erosive arthritis. It is estimated that over 90 percent of cats above the age of 12 suffer from joint cartilage erosion. Often, if your cat’s activity has slowed down, it is not due to old age but to DJD. It is the most common form of arthritis in cats. Multiple joints can be affected at once. Veterinary care should be sought for treatment of this condition as pain can be managed and the overall quality of life can be raised in most cases.

When something goes wrong inside of a cat’s joint, often from an injury or genetic disorder, arthritis begins to develop. Certain forms of arthritis, called degenerative joint disease (DJD), occurs when the inflammatory mediators that are released upon injury start to break down the cartilage in the joint at a rate that is far faster than the rate body can repair it. This condition is very painful for the cat and is generally progressive and irreversible.

One of the first signs that something is wrong is your cat’s obvious reluctance to get up after waking up from sleep. You may notice this and other symptoms worsening over time. All symptoms are as follows:

• Stiffness
• Lameness
• Wobbliness
• Abnormal gait when walking
• Reluctance to move
• Difficulty jumping
• Prolonged periods of laying down
• Pain
• Swollen joints
• No interest in play
• Lethargy
• Depression
• Weight gain
• Loss of appetite
• Aggression
• Bony growths on the joints

Degenerative joint disease (arthritis) is the primary cause of joint cartilage erosion in cats. Trauma is the main reason that DJD progresses. All known causes are listed below:

• Sprains
• Fractures
• Chronic wearing of joints
• Elbow/hip dysplasia
• Genetic predisposition (often seen in the Scottish Fold breed)
• Malformation of joints during development
• Obesity
• Aging
• Poor nutrition
• Immune system problems
• Osteochondrosis Dissecans (joint disease where cartilage forms cracks)
• Cranial Cruciate Ligament Rupture (ACL tear)

Diagnosing a cat with this form of arthritis is usually not difficult. The veterinarian will commonly ask about the cat's overall health and level of activity. The cat’s complete medical history will be requested. The vet will discuss symptoms and attempt to match them to signs of DJD. A careful physical exam will be conducted, with precautions taken to avoid causing added pain to affected joints. The vet will feel for swelling, heat, or tenderness around the joint area. 

Blood tests and urinalysis are generally requested during the visit. This will rule out all other possible causes and give a window into the cat's overall state of health. An X-ray, MRI or CT scan will be requested to assess how much the joint has already deteriorated, and check for the development of hardening soft tissue (osteophytes). In some cases a bone nuclear scintigraphy will be performed to locate abnormalities. 

While the damage of this condition cannot be undone, pain can be relieved and, in some cases, function can be improved for the cat. Certain treatments can stimulate the body's own joint repair and slow the progression of the disease. 

Non-Surgical Treatments

• NSAIDs: Nonsteroidal anti-inflammatory drugs can be prescribed for pain relief and swelling reduction. This helps the cat to function more normally.
• Chondroprotective Agents: These promote joint repair and counteract the degenerative process of DJD by normalizing fluid and cartilage in the cat’s joint. These agents include vitamin C, glucosamine and omegas 3 and 6.
• Opioids: In cases which pain is the main symptom and the cat is not a good surgical candidate, opiate painkillers such as buprenorphine may be prescribed. This can also aid in palliative care.
• Diet & Exercise: Encouraging weight loss for the cat by using a strict diet and promoting mild play can help stimulate the body to repair cartilage naturally.
• Physical Therapy: Treatments such as passive flexation and hydrotherapy can be used to help repair the joints. However, most cats strongly object to hydrotherapy.

 Surgical Treatments 

• Arthroscopy: This is a minimally invasive surgery where only small incisions are made. Tiny cameras are inserted to plan out the course of surgery and the special instruments are used through the same incisions to perform the surgery. Repair can be made to the shoulder, elbows, ankles and knees using this surgery. Recovery time is fast due to small healing areas. 
• Elbow/Hip Replacements: This is an expensive surgery that is only offered in select animal hospitals. The recovery time is 2-3 months, and the surgery carries higher risk.
• Metal Implants: In rare cases, metal implants may be surgically added to fuse a damaged wrist, toe, limb or spine joint. 

Any treatment that uses ongoing medications puts the cat at risk of developing kidney problems, so should be monitored carefully.

Most treatments offer improved quality of life for the affected cat. The prognosis is far better if the degenerative joint disease is caught and treated early, as damage done is not reversible. If the cat is obese or aged, the prognosis is generally worse than for young, fit cats. Cats suffering from genetic disorders tend to degenerate faster than those whose arthritis is injury-caused. The veterinarian will tailor a specific plan to maintain the cat's condition. It is advised to keep the cat indoors to reduce the chance of trauma.