Canine Arthritis         

Canine arthritis

Like humans, dogs can develop many forms of arthritis.  These forms are classified according to the inciting cause and behavior of the condition (see figure 1).  The following list describes several of the forms.

• Osteoarthritis is by far the most common form of canine arthritis, and is described in detail below. 
• Infectious arthritis results from growth of microorganisms in a joint, or the spread of an infection to a joint from elsewhere in the body.  For example, Lyme disease, a generalized infection caused by a tick-transmitted microorganism, can affect one or several joints.  Often an affected dog will show lameness than moves from one limb to another.
• Rheumatoid arthritis is uncommon in the canine (approximately 100 times rarer than in humans) and generally affects middle-aged to older small-breed dogs.
• Systemic Lupus Erythematosus (SLE) is a polysystemic disease that often affects joints.  Though the initiating cause of SLE is unknown, the disease ultimately results in the body’s immune system attacking components of the body’s own cells.  The process results in damage to many organs, including the joints, kidneys, lungs and skin.
• Adverse drug reactions can affect joints as well as other organ systems.  Antibiotics are the most frequent offender.  Certain breeds, such as Weimaraners and Doberman pinschers may be predisposed to such reactions.
• Juvenile polyarthritis of Akitas is one example of a breed-specific arthritis.  This rare, heritable condition affects the joints of young Akitas, and is often accompanied by a fever.  At present time the cause of this disease is unknown and the prognosis for an affected dog is poor.
• Other breed-specific arthritic conditions are reported in Shar Peis, Boxers, Beagles, Pointers, Weimaraners, Greyhounds and Bernese Mountain Dogs.  Though many of these conditions are still poorly understood, most are believed to be immune-mediated, similar to SLE.

What is canine osteoarthritis?

Osteoarthritis (OA) is by far the most common form of arthritis in the canine, affecting an estimated 20% of dogs in the US.  Also known as degenerative joint disease, OA is a slowly progressive disease involving the breakdown of the articular cartilage in a joint.  This cartilage is a specialized tissue that intimately covers the bone surfaces that contact each other.  It provides lubrication and shock-absorption for the joint, and prevents bone-on-bone contact, allowing frictionless, pain-free movement. Anything that causes abnormal forces within the joint can concentrate extra load on cartilage, damaging this cartilage and initiating OA.  There are many factors that can lead to such damage, including developmental skeletal abnormalities, obesity and traumatic injury.  The body’s inability to repair the injured cartilage results in permanent damage and the pain and inflammation of OA.

How do I know if my dog has osteoarthritis?

Because OA is a slowly progressive disease, it can be difficult for an owner to notice its onset in his/her dog.  Consequently, canine OA is grossly under diagnosed.  While human arthritis patients can readily describe the pain they feel, dogs tend to show that they are in pain in subtle ways.  In particular, a dog experiencing aching pain is unlikely to express discomfort by barking or whining.  Instead an owner should look for behavioral changes, such as slight alterations in gait and reluctance to engage in certain physical activities like jumping into a car or going up or down stairs.  The owner may also notice the dog becoming less willing to interact with people or other pets, and acting uncomfortable or depressed.

A veterinarian who suspects OA in a dog will typically begin by observing any gait abnormalities, feeling the joint for enlargement or swelling, and noticing a reduced range of motion.  Radiographs are often helpful as they can reveal characteristic changes in the bones and soft tissues of an arthritic joint.  It also may be valuable to analyze fluid taken from the suspected joint.  Additionally, the veterinarian may perform further tests to rule out forms of arthritis other than OA.

How did my dog get osteoarthritis?

Many of the developmental skeletal abnormalities that predispose a dog to OA are known to run in breeds.  The hip and elbow joints in certain large breed dogs and the knee in some small breeds are common sites for problems.  A person looking for a new puppy should take the time to research the orthopedic status of the parents.  There are different certification systems for the dam and sire which can help give the potential owner some assurance about the genetics of a new pup.  However no testing protocols can completely guarantee a healthy adult pet.

Aside from these heritable predispositions, environmental and lifestyle factors can have a major impact on the development of OA.  The most important of these is body weight.  Several studies have demonstrated a significantly increased risk of OA in overweight dogs.  Besides placing more stress on joints, carrying around extra weight tends to aggravate genetic skeletal abnormalities and predisposes a dog to traumatic injury.  Maintaining a dog in ideal body condition is one of the best ways an owner can prevent or slow the progression of OA.

What are the treatment options for osteoarthritis?

At the present time there is no cure for OA.  However, weight loss, lifestyle modification and medications for pain can greatly improve the quality of life for an arthritic dog.

The two most important non-medicinal approaches are weight reduction and exercise modification.  In many cases these two treatments can greatly diminish the clinical symptoms of OA.  Exercise for a dog with OA should consist of regular, limited physical activity and/or physical therapy.  Intense activity can exacerbate OA and therefore should be avoided. 

Medical treatment of OA centers on the use of non-steroidal anti-inflammatory drugs (NSAIDs) to reduce inflammation and pain. Dogs metabolize NSAIDs differently than humans and thus the exact drugs and dosages used do not mirror human medicine.  For this reason, an owner should never attempt to medicate a dog with a human NSAID by extrapolating from human dosage recommendations.  There are many NSAIDs designed for dogs, including several so-called COX-1 sparing drugs, which are associated with reduced gastrointestinal side-effects.  Diets rich in certain types of fatty acids are now on the market and there is promising data to support their use in the relief of OA pain.  Additional nutritional supplements such as glucosamine and chondroitin sulfate are also available.  While some initial data on these products is available, there is much to be learned (such as the correct dose and which compounds are most effective) before wide ranging recommendation can be made to support their use.

In the case of an extremely arthritic and debilitating joint, the owner and veterinarian may consider surgical treatment.  Surgical options include arthroscopic surgery, total joint replacement, or fusing the joint. Please check with your veterinarian or a board-certified veterinary surgeon (member of the American College of Veterinary Surgeons) before pursuing surgical options.

Authors: Owen Fink, BS, University of Georgia College of Veterinary Medicine, Athens, GA 

  Steve Budsberg DVM, MS, DACVS, University of Georgia College of Veterinary Medicine, Athens, GA