Glucosamine in Canine Osteoarthritis – Why use it when it doesn’t work?

Since 2000, more than 800 products containing dietary supplements promoted as treatments for osteoarthritis have entered the US market place alone. In 2008, the market for supplements such as herbal medicines, nutritional supplements was $20 billion and rising.

Surely, they must be doing something if we spend this much money on them? Maybe..maybe not. I still think they have a role to play so let’s explore the evidence a bit further.

Several Meta-analyses have recently tried to answer this question but results are conflicting. A Meta-analysis is a statistical procedure that integrates the results of several independent studies considered to be “combinable”. Although they can be performed badly, a well—conducted meta-analysis should allow a more objective appraisal of the combined evidence.

One such meta-analysis I read recently was published in American Family Physician

(2008;77(2):177-184) which you can download from www.aafp.org/afp. Their view was that although the evidence was not entirely consistent, most research suggests that glucosamine sulphate can improve symptoms of pain related to osteoarthritis, as well as slow disease progression in patients with osteoarthritis of the knee. The evidence for a proven effect of supplements in arthritis is generally weak. However, most would agree that glucosamine has the most evidence to support its use, particularly glucosamine sulphate.

However, glucosamine and/or chondroitin may not be helpful for patients with osteoarthritis of the hip or knee, according to the results of a recent meta-analysis reported in the September 17 2010 issue of the British Medical Journal. The authors of this paper concluded that  “Compared with placebo, glucosamine, chondroitin, and their combination do not reduce joint pain or have an impact on narrowing of joint space,” the study authors write. “Health authorities and health insurers should not cover the costs of these preparations, and new prescriptions to patients who have not received treatment should be discouraged.”

As with all published work, care should taken in basing all treatment advice on the results of a single study and limitations of this study should also be considered. These limitations include:

1.Different ways of measuring joint pain were used which could potentially threaten the validity of results.

2. Patients included in the trials may have had disease too severe to benefit from supplementation or pain too minimal to benefit from analgesic effects. One of the major difficulties I have always seen with any drug used in OA management is that OA is a very variable condition and it makes sense to me that the effect of any potential disease modifying agent will be dependent, to a greater or lesser extent, on the severity of the disease when the agent is used.

I think there is always a danger of ‘throwing the baby out with the bathwater’ if you take any one study in isolation.

The BMJ study did emphasise that glucosamine and chondroitin appear to be safe and they would not discourage people from taking them if they felt they helped.

The recent study does question their benefit and, as I have said in several areas if this website, claims for these supplements are often greatly overstated in sales copy. The fact they are safe and may help in some patients, and have the support of some studies would keep my overall view unchanged and I would still use a good quality oral glucosamine supplement as one part of my multimodal approach.

The secret is a balanced, integrated approach that doesn’t just focus on one factor such as supplements, diet or pain killers.

If you haven’t read it yet, I would refer you to this article on the website

Canine Arthritis – Why Treatments don’t work

I hope that is a useful summary. If it has helped you then please share it with your

friends. Thank you.

Best Regards

Andrew

,