On Sale But Is It Safe: Cosequin Double Strength Plus MSM Joint Healh Dog Supplement

Background

The manufacturer makes some lofty claims under the 'additional details' section of the product page:

Cosequin Double Strength Plus MSM Joint Health Dog Supplement gives your dog a unique combination of special ingredients formulated to support and maintain your dog’s joints. Its ingredients work together to: inhibit the enzymes that break down joint cartilage, maintain the structure of existing cartilage, and increase the production of new cartilage. That way, your dog’s joints are restored as well as maintained. Cosequin DS doesn’t just support and maintain your dog’s joint health; it supports and maintains your dog’s overall well being. Your dog will be able to move and play with improved mobility and less stress on joints. Cosequin Double Strength Plus MSM Joint Health Dog Supplement can support joint health in dogs of all ages and lifestyles

Not only do they say this stuff restores joints, but it makes new cartilage too.  Hmmm, sounds a bit too good to be true. 

The active ingredient is primarily Glucosamine Hydrochloride (from shellfish) with Sodium Chondroitin Sulfate (from cow cartilage) and Methylsulfonylmethane (MSM).  Glucosamine is a monosaccharide (simple sugar) derived from crustacean exoskelotens. Sodium Chondroitin Sulfate comes from cartilage (it helps resist compression) and is also a type of sugar.  Methylsulfonylmethane is a type of sulfate. 

Analysis

Are these ingredients safe?

Working backwards, Methylsulfonylmethane is generally believed to be safe and any issues were not differentiated from those seen in placebo groups. Sodium Chondroitin Sulfate is also generally considered safe, however care must be taken to be sure it comes from a biological source.  The FDA noted in 2008 that heparin imported from China had been contaminated with "oversulfated Chondroitin Sulfate" that is synthesized in the lab and the final product differs considerably from the naturally derived source.

Finally, Glucosamine is believed safe but there is some indication that it may be less so at high doses where there is concern for potential damage to pancreatic cells.  In some rare cases there are reports of worsening of chronic liver disease.  Though almost all glucosamine carries a standard shellfish allergy warning, that should not be a problem if manufactured properly as the allergy originates in the flesh but glucosamine derives from the shell.

In our review, it appears that the ingredients are likely to be safe when used properly.  However, there is an established tendency of human use to go above recommended guidelines when efficacy is not apparent.  The most often recommended dose in humans is 1,500 mg vs the 600 mg in the Cosequin supplement for dogs.  IMPS considers the relative level in the Cosequin to be too high, but that does not in and of itself imply that amount is unsafe.

Are these ingredients effective?

To be short, probably not.  All of the ingredients above have been touted since the 1980s as having beneficial effects, most frequently for osteoarthritic issues.  However, clinical studies are few and far between and many have been less than rigorous or of small sample sizes.  Meta reviews have at best indicated only a mild positive effect and most are unable to point to a clear beneficial outcome.  IMPS points to a recent Consumer Reports review of joint supplements for humans:

In a large, multicenter trial published in 2006, researchers found some evidence that glucosamine and chondroitin alleviated pain in patients with moderate to severe knee osteoarthritis, the most common type. But subsequent studies have not confirmed that finding. And treatment guidelines issued in May 2013 by the American Academy of Orthopaedic Surgeons don’t recommend glucosamine and chondroitin supplements, citing lack of efficacy.

Verdict: Split

Safety: A-   probably safe.  Watch for any adverse signs when given to dogs with liver disease or those taking blood thinners.

Value: D  most users will not see any effect that can be conclusively pinned down on the supplement. In humans, the "placebo effect" may help, not so in pets (but maybe in their hopeful owners). Not worth the money, though if you have tried everything else, the sale price makes a short test not too costly.