Arthritis in Dogs

Causes, Symptoms, and Treatments

by Dr. Audrey Harvey, BVSc (Hons)

Arthritis in dogs is a very common condition medical condition. It is basically an inflammation in a joint, and it can affect any part of your dog's body. The result is pain, difficulty in moving around, and a significantly reduced quality of life.

Every joint involves two or more bones in close association with each other. At the end of these bones is articular cartilage: this cartilage provides a smooth surface for the bones to move against each other easily. The joint also contains a thick fluid which acts as a lubricant and shock absorber, and this too protects the bones from wear and tear.

When arthritis in dogs develops, the cartilage becomes rough and worn, and the joint fluid becomes watery. There is less lubrication and cushioning in the joint, and movement becomes uncomfortable. As the cartilage continues to wear away, bone will eventually rub on bone. This is very painful indeed.

Causes of Dog Arthritis

There are three causes of arthritis in dogs:

1. Infectious Arthritis

Infectious arthritis results when bacteria or other organisms find their way into a joint. This can happen if a dog sustains a wound which penetrates a joint and allows bacteria to enter. It can also happen if there are foreign organisms in a dog's bloodstream which are then carried around the body and into the joints (septic arthritis). The dog's immune system fights the infectious organism inside the joint, which results in pain and inflammation. This is the least common type of arthritis, and can affect any dog at any stage of their life.

2. Immune Mediated Arthritis

Immune mediated arthritis occurs when a dog's own defenses against disease don't work as they should. The immune system, which is supposed to attack foreign invaders such as bacteria and viruses, inappropriately attacks the dog's own tissues. The result is joint pain and swelling.

There are two types of immune mediated arthritis in dogs. The erosive form, known as rheumatoid arthritis, wears away the articular cartilage and underlying bone, and tends to affect small breeds of dog such as the Shetland Sheepdog and the Poodle. The non-erosive form doesn't harm the cartilage and bone, but inflammation still leads to pain and swelling. It tends to occur in association with disease in other parts of the body, such as cancer, and is more likely to affect large breeds including the German Shepherd or Doberman Pinscher.

3. Degenerative Arthritis

Degeneration in the joint associated with age or abnormal wear can result in cartilage damage and lead to arthritis. This is by far the most common type of arthritis in dogs, and it can occur in dogs of any age.

Younger dogs can develop degenerative joint disease if they have an untreated orthopedic abnormality such as hip or elbow dysplasia. It is easy to see that any breed that is affected by hereditary orthopedic disease, such as the German Shepherd, Rottweiler or Labrador Retriever, is at risk of developing this form of arthritis at a young age.

Trauma to a joint can lead to arthritis. For example rupture of the cranial cruciate ligament in a dog's knee can cause the knee bones to rub abnormally against each other. If it isn't surgically repaired, it usually leads to cartilage damage and arthritis. This type of injury may be more common in sporting dogs such as those that participate in agility training.

Elderly dogs can also develop this type of arthritis due to many years of wear and tear on their joints, especially if they are overweight or obese.

Symptoms of Dog Arthritis

One of the first indications that your dog may have arthritis is that they develop a limp. Sometimes it is hard to tell if any particular leg is sore, but you will notice that they are walking differently.

The sore joint may be swollen, and it will hurt when it is flexed and straightened. Your dog may bite at the painful area to try and relieve their discomfort. They may also be slow at getting up and lying down.

If the arthritis is caused by infection, then your dog may have a fever, and be lethargic and off their food.

Immune mediated arthritis in dogs tends to affect more than one joint. It causes a shifting lameness, where your dog will appear to limp on one leg, and then on another. They may shuffle or walk stiffly, because each step hurts. They are often listless and have a high temperature, and the lymph glands in the area of the joint will be enlarged.

It often takes a visit to your veterinarian and some testing to work out the cause of your dog's arthritis. In some cases, the cause will be obvious. If you have a senior dog with a generous waistline, then they are very likely to be suffering from degenerative joint disease. Similarly if your dog has a history of a wound over a joint, then it is possible they have an infectious arthritis.

Your vet may recommend x-rays, blood tests and even collecting a sample of the fluid inside the joint for analysis.

Treatment for Dog Arthritis

The treatment for your dog's arthritis depends on the cause.

If they have infectious arthritis, treatment must include antibiotics to kill the infection. This is accompanied by non-steroidal anti-inflammatory drugs such as carprofen (Rimadyl), meloxicam (Metacam) or deracoxib (Deramaxx). These drugs are extremely effective painkillers and will reduce the inflammation in the joint, but they do have some side effects. They cause irritation to the lining of the stomach, which can lead to ulcers. They can also affect the kidneys, so watch for excessive drinking and urination. The infected joint can also be flushed out with warm saline if necessary.

Immune mediated arthritis is treated with medication to suppress the immune system. Prednisolone, azathioprine (Imuran) and cyclophosphamide (Cytoxan) are the main drugs used in managing this condition. They are effective at relieving the symptoms of arthritis, but may cause their own problems. Long term prednisolone can result in a condition called Cushing's Disease, which is caused by an excess of cortisol in the body.

Symptoms include excessive thirst, increased urination, weight gain and liver abnormalities. Imuran and Cytoxan suppress the immune system by reducing the production of white blood cells in the bone marrow. By doing this, these drugs leave your dog susceptible to other infections, because they may not have enough white blood cells to fight them off.

Degenerative joint disease is usually managed with pain relief. Firstly, non-steroidal anti-inflammatory drugs can be used to control pain and make your dog more comfortable. Some drugs are more effective in individual dogs than others, so if your dog isn't responding as well as you'd like, try another medication.

As already mentioned, there are potential side effects associated with them. Some dog owners prefer to try more natural therapies such as acupuncture, which may ease discomfort with no side effects.

There are some non-specific ways of treating arthritis in dogs, irrespective of the cause. Glucosamine and chondroitin can increase the production of joint fluid and encourage cartilage healing. Fish oil contains a specific balance of omega fatty acids which can act as a natural anti-inflammatory, and may help to reduce inflammation in the joint. Weight loss will help any dog with joint pain, because their sore limbs won't have to carry those extra pounds. Lastly, if your dog is hurting, then allow them to rest as much as possible. By reducing joint inflammation with these methods, your dog may need less medication, which will then reduce the risk of side effects.

Arthritis in dogs, although painful, can be managed by working closely with your veterinarian. With the appropriate treatment, they can again enjoy their favorite activities free from pain and discomfort.

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