What is degenerative joint disease?

Degenerative joint disease (DJD), also known as osteoarthritis, is a progressive condition of the joints characterized by gradual cartilage breakdown, bone spur formation, inflammation, pain, and periarticular scar tissue formation. It is very widespread in both dogs and cats, especially as they get older, and has been identified as the most common cause of chronic pain in pets. 

DJD can be classified as primary or secondary. Primary DJD is an age-related process in which cartilage cells, called chondrocytes, begin to exhibit decreased activity, which causes the cartilage to become dehydrated and lose its elasticity. In this state, the cartilage is much more vulnerable to cumulative damage from daily activities. This damage results in the release of inflammatory mediators and enzymes that perpetuate cartilage breakdown and inhibit healing. Secondary DJD occurs when abnormal forces cause damage to normal healthy cartilage over time. These abnormal forces may be the result of trauma, developmental conditions (hip dysplasia, elbow dysplasia, osteochondrosis dissecans, luxating patella, etc.) or degenerative processes such as cranial cruciate ligament tears. 

What are the symptoms of degenerative joint disease?

In dogs, the most common signs of DJD include lameness, stiffness, and reluctance to use stairs or engage in vigorous physical activity. Lameness and stiffness are often most pronounced after a dog gets up from a period of rest, and are often exacerbated by cold, wet conditions. Usually the lameness is initially intermittent, and may progress to become constant over time. 

In cats, the most common signs of DJD include a general decrease in activity (often mistaken for a sign of normal aging), reluctance to jump or use stairs, and decreased grooming activity. A noticeable limp is much less commonly seen in cats, but may be observed in some cases. 

How is degenerative joint disease diagnosed?

Degenerative joint disease is diagnosed with a physical exam and x-rays. On exam, thickening around the joint (from scar tissue accumulation) and increased joint fluid (called effusion) are often palpable. A popping or cracking may be felt or heard when the joint is flexed and extended, and range of motion is typically decreased to some degree.  The patient frequently exhibits some degree of discomfort on palpation and manipulation of the joint, although this can be subtle. Arthritic changes that can be seen on x-rays include joint effusion (increased fluid within the joint), narrowing of the joint space (reflecting loss of cartilage), sclerosis of the subchondral bone (the bone surface beneath the cartilage), osteophytes (bone spurs), and mineralization of portions of the joint capsule or ligaments. The magnitude of abnormalities on x-rays do not always correlate with the severity of symptoms, so x-rays must be integrated with the history and physical exam to determine the best treatment for a specific patient. 

How is degenerative joint disease treated?

The goals of DJD treatment include slowing the progression of disease, enhancing mobility, and improving comfort. Treatment typically involves four primary components:

• Medications and nutraceuticals
• Weight management
• Physical rehabilitation therapy
• Alternative therapies

Medications and nutraceuticals are administered to improve joint health and decrease pain and inflammation. Nutraceuticals that improve joint health, called chondroprotective agents, include glucosamine, chondroitin, and polysulfated glycosaminoglycan. These components of healthy cartilage help to inhibit further cartilage breakdown and promote healing. They are most effective if started early in the progression of arthritis, but may be helpful even in advanced cases.Omega-3 fatty acids (EPA and DHA) have been shown to decrease inflammation throughout the body. Other nutraceuticals with potential anti-inflammatory properties include methylsulfonylmethane (MSM), avocado/soybean unsaponifiables, Boswellia (frankincense), and curcumin.

The class of medications most frequently relied upon to control the pain and inflammation of DJD is non-steroidal anti-inflammatories (NSAIDs). Carprofen (Rimadyl), deracoxib (Deramaxx), firocoxib (Previcox), and meloxicam (Metacam) are all commonly used in dogs, while meloxicam is the only NSAID approved for chronic use in cats. While NSAIDs are typically well-tolerated, it is possible for them to cause GI inflammation (ulceration in severe cases), liver impairment, and progression of kidney disease. Any patient on NSAIDs long-term should have an exam and bloodwork every six months to ensure that no adverse effects are developing. Sometimes when a patient’s pain is severe enough to persist in the face of NSAID therapy, additional pain medications may be prescribed, including tramadol, gabapentin, and amantadine. 

Weight management is an essential component of DJD therapy. Excess weight significantly increases the load on a pet’s joints, accelerating the progression of the disease. Significant improvement in symptoms can be seen with weight loss alone, potentially reducing the need for daily medications and other treatments. A combination of a weight loss diet (such as Hill’s Metabolic Prescription Diet) and low impact exercise regimen (such as swimming or underwater treadmill walking) can help even pets with advanced joint disease to shed pounds. The impact of weight reduction on an arthritic pet’s quality of life cannot be overstated.

Physical rehabilitation therapy has multiple significant benefits beyond weight loss for the arthritic patient, including increased flexibility, strength, comfort, and mobility. Modalities that are frequently used to help arthritic patients include:

• Heat therapy, which helps to reduce pain and stiffness while increasing circulation 
• Class IV laser therapy, which has been shown to decrease pain and inflammation and promote tissue repair 
• Therapeutic ultrasound, which promotes relaxation of the tissues surrounding a joint, thereby improving suppleness and flexibility and easing pain
• Transcutaneous electrical nerve stimulation (TENS), which aids in the reconditioning of atrophied muscles, and has also been shown to relieve pain
• Stretches, massage, and range of motion exercises, which improve joint mobility and limb use
• Exercises geared toward improving balance and proprioception, which enhance mobility
• Underwater treadmill exercise, which provides buoyancy to decrease the load on a patient’s joints, allowing for comfortable joint mobilization which contributes to improved joint health, while also providing resistance to build muscle and improve cardiovascular fitness as well as gentle heat to relax and soothe tissues 

Alternative therapies that may be added into a treatment protocol include stem cell therapy, platelet rich plasma therapy, and acupuncture. Stem cells can be collected and purified from a sample of the patient’s own body fat and injected into arthritic joints. These have been shown to reduce inflammation and aid in cartilage healing and regeneration, allowing for significant improvement in mobility and reduced need for pain medications. Platelet rich plasma is a fraction isolated from a patient’s blood that can similarly be injected into diseased joints. This contains growth factors and anti-inflammatory compounds that have been shown to aid in tissue repair processes within the joints. Acupuncture is an alternative modality that utilizes extremely fine needles inserted at precise locations on the body to reduce pain; there is some evidence that this may also play a role in decreasing inflammation and promoting blood flow to target areas. 

Following a consultation, physical exam, and x-rays, your veterinarian can custom-design the DJD treatment program that is optimal for your pet to get them on the road to restored comfort and mobility.

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