Canine Arthritis

Posted by  on June 15, 2010

Just as humans experience joint pain as they age, dogs, too, are susceptible to arthritis and degeneration of the joints. Common causes of joint pain are hip dysplasia, chondrodysplasia, old fractures, and arthritis. By far, the most common of these is arthritis, also known as osteoarthritis. It affects one in every five adult dogs and is one of the most common reasons for veterinary visits.

Learn how to tell when your dog is having problems with his joint health and what you can do help ease the pain.

Normal joint structure and function

A joint, such as the hip or knee, is formed when one bone connects to another. There are three basic types of joint in a body: fibrous, cartilaginous, and synovial. A fibrous joint is totally immovable, such as those between the bones of the skull. A cartilaginous joint is slightly movable, such as those between the vertebrae of the spine. The synovial joints are those most prone to arthritis because they are totally movable, creating a rubbing motion between the two bones.

Each synovial joint is encased in a synovial membrane or capsule. Inside the capsule and between the bone ends is a layer of smooth cartilage that acts as a shock absorber. Synovial fluid bathes the area, keeping everything moving smoothly, like a well-oiled machine. As the dog takes a step, the force of impact of the dog’s body weight hitting the ground is transferred to the cartilage, and no pain is experienced.

Tendons attach the muscles surrounding the joint to the bones, while ligaments attach the bones on each side of the joint to each other, holding the joint in alignment. A strain occurs when the muscle is stretched too far, while a sprain indicates that a ligament has been over-stretched. Both of these will cause joint pain, and must be ruled out before assuming that arthritis is the cause of the pain. Typically, they are distinguished by their short duration (usually two weeks or less) and the tendency to improve with time, while arthritis only gets worse.

Degenerative joint disease

Osteoarthritis is a form of degenerative joint disease in which the cartilage wears away from the joints. Cartilage itself has no pain nerves, so when a dog has healthy cartilage, he feels no pain when he moves. When a dog is young, the cartilage that gets worn away through daily use is readily replaced by new cartilage, keeping the joints functioning without pain. However, with age, the cells that produce new cartilage are unable to keep up with the cartilage that gets worn away, and the dog begins experiencing joint pain because the bones of the joint begin to rub on each other without the protective cartilage to act as a shock absorber. In contrast to cartilage, bones carry pain nerves, causing pain whenever the bones rub against each other.

Osteoarthritis most often affects the hips of a dog, but can occur in any joint, particularly the synovial type. Joints which have been subjected to trauma such as sprains, strains, fractures, or dysplasia are especially susceptible. Dogs who are overweight put excessive pressure on their joints, increasing their chances of developing arthritis at a relatively young age. Similarly, larger breed dogs are more likely to develop joint problems than smaller breeds.

Symptoms of joint pain

When your dog begins to develop arthritis, he will also begin to develop inflammation in the affected joint. Early diagnosis and treatment are vital because you can more easily rebuild cartilage if you catch the disease early in its progression. Your dog may display pain by holding up the affected paw or by favoring the leg which has a bad joint. The dog may pull his leg away from you in pain when you push on the joint or try to move the leg. You may notice that the dog has his worst pain in the morning, or after lying in one position for awhile, and the dog may whimper or cry out when he moves his leg the wrong way.

If you examine the painful leg, you may find swelling around one or more of the joints. The joint may also be warm, and the skin surrounding it may be reddened under the dog’s fur. These are the four classic signs of inflammation, defined in ancient medical Latin as rubor, calor, tumor, and dolor (redness, heat, swelling, and pain).

Extreme care must be used when examining a dog in pain, as even the most docile dog may lash out against someone who is causing him pain. Dogs in pain have been known to snap at the vet or even their closest friends who manipulate a sore joint. It is best to have a friend or another family member hold the dog’s head while you are examining the joint.

Diagnosis of canine arthritis

By simply observing your dog for the classic signs of inflammation, you may have a pretty good idea that he has arthritis. However, a definitive diagnosis requires an X-ray of the joint, which will show an irregular bone margin in the joints. Normally, the ends of the bones are smooth and rounded, but in an arthritic joint, the bone ends become irregular.

In addition, joint fluid may be extracted and examined for evidence of a breakdown of the cartilage cells and synovial fluid, although this is rarely done.

At-home treatment of osteoarthritis

The most basic treatment is to make sure your dog maintains the proper weight. Losing weight takes some of the stress off of the joints, which will make your dog much more comfortable.

The next important at-home treatment is to rebuild the cartilage by using chondro-protective agents to help build up the cartilage. The most common medication used to protect and rebuild cartilage is glucosamine-chondroitin. Other minerals and vitamins such as ester-C and MSM may be added to the mixture to improve its effectiveness.

Glucosamine-chondroitin products are generally given at a relatively high dose for 6 weeks to two months to kick-start the production of cartilage, then the dosage is cut in half and maintained for the remainder of the dog’s life. Consult your veterinarian for the correct dose, based on your dog’s weight.

Other things important to joint health are to bring down existing inflammation and to keep the dog in good physical condition. Inflammation reduction is accomplished with any of a number of pills, the cheapest and easiest to procure being good-old buffered aspirin. Tylenol (acetaminophen) and Advil (ibuprofen), however, are toxic to dogs and should never be given.

Making your dog more comfortable

Even if your dog is not overweight, physical fitness is extremely important. Low-impact exercise is best because it avoids further damage to the joints. The best exercise of all is done in a pool, but if this is not possible, short walks can be used. The goal of whatever exercise you choose for your dog is to improve the range of motion around the joint while building muscle and limiting wear and tear on delicate joints.

It is important to develop and stick to an exercise routine. For example, working your dog only on the weekends will do more harm than good, as the dog’s joints will stiffen after exercise and not get loosened again until the next weekend. Your veterinarian can help you develop a program that will be both fun and beneficial to both you and your dog.

Provide a warm area away from drafts for your dog’s bed, and consider a sweater that covers the affected joint area, as cold, damp weather causes joint pain to worsen. A firm, orthopedic bed may also help to distribute the dog’s weight more evenly, reducing pressure on his joints as he sleeps. In addition, getting up out of an orthopedic bed may be easier for your dog than standing up from a cold floor or non-orthopedic bed.

Massage therapy may also help to improve your dog’s range of motion, relax stiff muscles, and relieve pain. Starting with just light petting to build trust, slowly build up to gentle kneading of the muscles around the affected joint using small, circular motions. Work your way out to the adjoining muscles of the leg. When you have finished the massage, you may apply warm, moist heat by using a heating pad set on top of a damp washcloth. Make sure to keep the heating pad set on low and apply it for no more than 10 – 20 minutes at a time.

Treatment of advanced canine arthritis

If daily aspirin is not sufficient to bring down the inflammation, prescription non-steroidal anti-inflammatory drugs may be used. Examples are carprofen and etodolac, both of which are powerful painkillers, but each of which has side effects. If you prefer a more holistic approach, there are herbal supplements which may be effective against both pain and inflammation. Consult a holistic veterinarian for advice on herbs and even acupuncture, which can be used to reduce pain.

The most aggressive treatment for canine arthritis is surgery, which can replace the diseased joint with a synthetic prosthetic. This is a quite expensive option, and should be the choice of last resort.