Gena sent in a question about her dog's arthritis. Apparently, little Piglet has problems with his knees bothering him. Many pets of all sizes suffer from osteoarthritis, so this is a good topic for discussion.
When most people say "arthritis", they are meaning what doctors call osteoarthritis. This is different than rheumatoid arthritis, which is a disorder of the immune system. Osteoarthritis is wearing and tearing on the joint surfaces over time. Certain breeds can be prone to this and orthopedic injuries can increase a dog's risk of it developing. Within a joint there are some basic structures: synovial fluid, which acts as a cushion and lubricant; hyaline cartilage, which covers the bone and helps with smooth, low-friction movement; ligaments and tendons, holding bones together; and the bone itself, underlying these tissues. As a joint deteriorates, the cartilage begins to wear off. As it does, it exposes the underlying bone. When bone contacts cartilage or another bone, that touch and movement causes pain and inflammation.
Once degerative changes begin in the joint, they are pretty much irreversible. Truly degenerative joint disease (DJD) will never return to normal, and can result in some extensive changes in the shape of the bone as the body tries to compensate for abnormal movement or instability. Even surgery can only do limited things to improve the condition, and are usually small changes such as removing bone spurs.
The keys to improving the lives of arthritic patients lies in helping with pain and inflammation. This can be accomplished through several means. One that most people are familiar with is prescription anti-inflammatory medications. The category of drugs is called "non-steroidal anti-inflammatory drugs" and is commonly abbreviated as "NSAIDs". You are already familiar with these products for human use as acetominophen, ibuprofen, naproxen, and many others. In veterinary medicine we have Rimadyl, Etogesic, Deramaxx, Melicam, and several others. Though they are all in the same category of drugs, they have slightly different efficacies between patients, and slightly different potential side-effects. That's why Tylenol works better for some people than Advil, or vice-versa. These medications help to reduce pain and inflammation, and can be the only thing to really help pets. They are not without potential dangers, though, especially with continual, long-term use. Currently these medications are available only by prescription (at least, in the US), and you should consult with your vet on these options. I do not recommend using human medications in dogs unless you are under a vet's instructions to do so. Dogs and cats are more susceptible to the side-effects than humans are.
Besides prescription analgesics, there are other things that can help, and I usually recommend them as a first choice unless the patient's pain is extremely bad. Glucosamine and chondroitin supplements can work wonders, and are readily available over-the-counter. They help to increase the lubrication of the joint, and can rebuild some of the cartilage. Numerous studies have shown their efficacy, and I have seen many of my patients dramaticly improve on them. They will take 2-4 weeks to show an effect, so don't give up on them after a few days. Many pet foods now have them included in the diet, especially for large breeds. There really are no side-effects, so they're a great supplement to use. Make sure to use one designed for pets, though. Even if the basic ingredients are the same as a human equivalent, we have a different digestive system and so the ingredients may not be absorbed as well if you use a human product.
Along the same lines is MSM, a natural dietary sulfur. This is another nutritional supplement, and works differently than glucosamine. MSM will act as a natural anti-inflammatory, which can help reduce discomfort. Using glucosamine and MSM together form a two-pronged approach that may eliminate or prevent the need for NSAIDs.
It is also very, very important to get your dog to a normal weight. Obesity can dramatically increase the pain of arthritis. First, there is extra pressure on the joints that the body was not designed to hold. Second, fatty tissue has been found to produce numerous hormones and biochemicals. Rather than being an inert substance, it actually is a very active one. These chemicals have been shown to increase inflammatory reponses in the body, which is one of the problems with arthritis.
If you have a pet with arthritis problems, talk to your vet. They may recommend x-rays to assess the amount of damage, and whether or not surgery is an option (as it may be in certain types of hip disease). They will also help design a management program that best suits your pet's needs.