Ron Hines DVM PhD 9/25/07
Arthritis occurs in dogs and cats and people in several ways. It can come about due to an injury to a joint, as an inflammatory disease of the bone, due to improper shape or conformation, improper nutrition or due to the ravages of time. This article focuses on the last cause, joints wearing out due to the passage of time. The advice, however, is useful in all forms of arthritis.
When you consider how soon mechanical mechanisms wear out, it is really remarkable how long natural joints can function. Nature's solution to motion is to coat two moving surfaces with a smooth cushiony membrane (symposium), immerse the space between the surfaces in an oily fluid and bind the two together with elastic sheets and ligaments. The secret of the long-term success of this apparatus is that its components are all living and capable of repair. As we age, this repair process becomes less successful and makes errors. With repeated movement throughout the years several things begin to happen. The elastic sheets and ligaments begin to stretch causing looser, more traumatic joint motion. This in turn bruises and erodes the joints smooth surfaces causing inflammation. As these surfaces continue to move, the inflammation causes new bone to be laid down in the way of motion where it does not belong and bone to be reabsorbed from where it is needed. We call the sum of all this arthritis.
The problems that lead to arthritis begin quite early in the pet's life but are not noticeable at that time. Choosing a breed of pet that has been bred for abnormal bone structure such as bulldogs or Persian cats mean that arthritis will occur sooner than if a more wolf-like or feral cat breed had been picked. Smaller breeds of dogs tend to have fewer problems than the large breeds. It is important that you keep your pets toenails clipped properly so their normal gait is not restricted. Overgrown toenails could be thought of as wearing shoes with improperly shaped soles and heels – they place strain on the joints that support them. A very important caution in preventing or delaying arthritis in later life is not to overfeed puppies – especially puppies of larger breeds. Puppy chows, feed free choice (all they will eat) is not in the long-term interest of your pet. It has been found that if you feed less than the pet is willing to consume it will mature slower with stronger joints and ligaments and even live a longer life. Puppies that eat too much gain weight faster than their poorly calcified joints can support it. They develop loose overly flexible joints, which are a starting point for arthritis. Later in life, it is important that your pet remains trim and not overweight. Trim dogs develop less arthritis and if the do, it occurs later in life. A moderate amount of daily exercise like taking walks with your pets also delays arthritis. Hot tubs, whirlpools and swimming are great.
Lets say that your pet is already showing the morning stiffness and intermittent lameness that signals arthritis. What are some of the things you can do? First, if your pet is overweight try feeding less of a low caloric diet. Many are marketed through supermarkets. If you are not strong willed enough to cut the pet's total food intake, purchase a prescription, weight reduction diet or supplement its diet with low caloric items such as cooked cabbage, green beans and carrots. There are a variety of nutritional supplements on the market today that might improve your pet's joint function. Some are prepared from extracts of cartilage. Others are formulated from the glycosoaminoglycans found in clams. Some have other ingredients added. None have been adequately tested scientifically to prove that they work but none will cause harm to your pet.
If the pet is not overweight, you can try daily doses of aspirin. I generally give about 5 mg per pound body weight once or twice a day. (please read email at end of this letter). Others have used double this dose. Like people, some dogs tolerate aspirin while others do not. Side effects are lack of appetite, vomission, diarrhea or dark stools. If any of these events occur you must lower the dose or discontinue it altogether. Never give aspirin to cats! Aspirin and all other anti-arthritic drugs are often referred to as NSAIs (non-steroidal anti-inflammatory drugs). All the older ones, such as aspirin, ibuprofen and indomethacin are known for causing stomach problems in people and pets. Three newer ones with less of this side effect and which are approved for pets are carprofen (Rimadyl, Pfizer) and etodolac (Eto-Gesic, Wyeth Ft.Dodge) and meloxicam (Metacam, Merial). The first is a twice a day product, the second two, once a day. All three of these products seem to really help old dogs get about again. They cannot be used in cats.
There are many other scientifically unproven treatments for arthritis in people and pets. Everything from magnets to acupuncture have been used. I cannot tell you that they do work, but little is lost in trying them if you wish.
A point eventually comes when the drugs mentioned are not enough. In these pets the carefully supervised use of cortisone-type drugs will often buy extra mobility time for your pet. Steroids are powerful drugs. The most commonly used ones for arthritic problems are prednisone and prednisolone. They are best given no more frequently than every second or third day. They relieve inflammation throughout the body but also cause increased appetite and thirst, fluid retention, liver enlargement and other changes. Do not fear cortisone drugs too much. These drugs have saved many lives. Any person with an organ transplant remains on one of them the rest of their lives. The secret of success with them is to control weight through diet and to give as little of the medication as infrequently as possible so you can enjoy the company of your pet as long as God allows.
Within the last year,new NSAID medications similar to Rimadyl have been approved by the FDA for use in dogs. They are deracoxib (Deramaxx, Novartis) tepoxalin (Zubrin, Schering), meloxicam (Metacam, Boehringer Ingelheim) and, most recently firocoxib (Previcox, Merial). Competition between these products has not made the prices of this class of medications more reasonable. Most are now offered in flavored tablets that are easy to administer. I do not know of any studies that rank one product better than another.
Many veterinarians sell or suggest glucosamine and chondroitin as a remedy for arthritis. Physicians do the same in human medicine. Data on the benefits of these products is very soft. Despite this, the need to include them has become an urban legend. In studies paid for by the manufacturers themselves, these products showed a slight positive effect. However, when the studies were not sponsored by vested interests (the producers) no beneficial effect could be measured. As example, the Harvard Life-time Study of Health Professionals which is one of the most reputable studies conducted in the US, found that these products had no beneficial effects whatsoever. Manufacturers now often include other elements and vitamins in their tablets and claim that the beneficial effects of chondroitin and glucosame are dependent on these additional agents. However, these claims are dubious and not scientifically supported because none of the additions are known to have beneficial effects on arthritis when given alone or in combination.Note: I was under the impression that glucosamine sulphate had no potentially deleterious effects on the body of humans or pets. However, an article published in the Lancet was recently brought to my attention that states that glucosamine sulphate is capable of affecting blood glucose concentration as well as the level of circulating insulin. This same article suggested that the Compound be used with caution in humans with diabetes. A recent study conducted at Harvard University and another reported in the veterinary literature did not find glucosamine to be measurable effective in preventing or reducing arthritis in pets or humans. The only studies that found a mild beneficial effect were paid for by the companies that sell the product. Independent studies found that they were of no value.
