Dealing with Arthritis in Your Dog

Dealing with Arthritis in Your Dog or Cat

Arthritis occurs in dogs, 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 (synovium), 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 joint's 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, means that arthritis will occur sooner than if a more wolf-like or feral cat breed has been picked. Smaller breeds of dog 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 over-feed puppies - especially puppies of larger breeds. Feeding 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. 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 they do, it occurs later in life. A moderate amount of daily exercise like taking walks with your pet also delays arthritis. Hot tubs, whirlpools and swimming are great.

Let's 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 the e-mail at the end of this article). Others have used double this dose. Like people, some dogs tolerate aspirin while others do not. Side effects are lack of appetite, vomission, diarrhoea 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 NSAI's (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), 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 has 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, two new NSAID medications similar to Rimadyl have been approved by the FDA for use in dogs. They are deracoxib (Deramaxx, Novartis), tepoxalin (Zubrin, Schering) and meloxicam (Metacam, Boehringer Ingelheim). Competition between these products may make the prices of this class of medications more reasonable.

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.

21/04/06 - Dear Dr. Browne,

I hope you do not mind my addressing you as Dr. prematurely - you will soon be called that for the rest of your life.

Thank you so much for your perceptive letter regarding aspirin. It is true; aspirin can have side effects associated with gastric and intestinal erosions. And it is also certainly true that a veterinarian using blood tests, would be the first to detect such problems. I am told that our Food and Drug Administration would not allow Aspirin to be sold as it is today in the US if it were a new drug. But that said; I know of no present or past medication, used in man or animals that have a proven effect without potential side effects too. These are usually dose-related. In America, aspirin is still considered safe enough to be sold over the counter, in most food stores, variety stores and pharmacies.

However, as in people there are, as yet, unknown differences in Gastro-intestinal protective processes in dogs and many that allow certain individuals to have no problems consuming aspirin at suggested levels, while others cannot tolerate aspirin at all. To the best of my knowledge, none of the newer non-steroidal anti-inflammatory agents have been proven to be more effective than common aspirin. They were primarily developed by the International Pharmaceutical Corporations for their sales potential in humans - there is no profit to be made in selling aspirin or other effective medications that no longer have patent protection.

As physicians do, I stress that clients must monitor their dogs for in-appetence, vomission, diarrhoea or melena (tary stools). Faecal blood tests used in humans seem to always show false positive in dogs. The result of gastric or intestinal erosion can be blood loss and anaemia. So you are wise in suggesting that a PCV (Hct) be run from time to time during the first six months or year of administration and occasionally thereafter. Actually, I have read of more side effects due to the administration of carprofen or etodolac in America that to aspirin. I believe side effects to the newer patented NSADs , Metacam (Mobic) are less, but I do not know how it compares to aspirin in this effect. I suggest none of these agents be used in cats, but arthritis is much rarer in older cats. Again, from what I have read, organ damage due to aspirin tends to be caused by too large a dose. I always recommend the smallest possible dose that gives the pet relief and mobility and you are wise to suggest a veterinarian monitor all drug use in pets.

Most veterinarians recommend between 5 mg and 10 mg per pound of the dog's weight every 12 hours. Going on the safe side, a recommended dosage of aspirin of about 5 mg/lb which seems to work well for most dogs is wise. I do not recommend coated aspirin because I have read that dogs lack the lactase, required to break down some enteric coating. For some unknown reason, small and toy breeds seem to tolerate less mg of aspirin per pound.

It is only through kind letters like yours that I can rethink what I have written.

There are few other good options when treating arthritis in dogs.

Studies completed in 2006 at the Harvard School of Public Health in Boston, Massachusetts concluded that chondrotin and glucosamine products, sold by many veterinarians as an aid to arthritis, are worthless in humans (and so, probably in dogs as well). They are made from an extract of Pernia canicularis, the blue lipped mussel. Chondrotin is extracted from bovine cartilage. I get their bulletins because I am one of their study subjects. They will monitor our habits and the results of our habits until we all die. There was never any scientific reason to expect them to work. It is much like the Chinese practice of eating turtles to gain longevity or testicles for sexual performance.

In my experience, the only alternative to NSAI's that seems to help in arthritis are the corticosteroids. And you know of their severe side effects. I use them only when I expect the dog to live less than six months more. Periodic, intra-articular injections of methylprednisolone acetate have less systemic effects than circulating corticosteroids so I use them first.

The only other medications that may work are the opiate alkaloids. They cause agitation in cats and horses but seem to work well in dogs. However, the dog dose of opiates seems to be about four times that in humans. Also, there is too much of a chance of diversion of the tablets to humans. And if taken according to the dog directions on the pill vial, are often fatal to man.

By Dr. Ronald Hines DVM PhD
Consult With Dr. Hines

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