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Everything You Need to Know About Joint Chews in Dogs and Cats

There are more joint chew supplements on the market for dogs and cats then we can count, but the big question remains, do they actually work?  The short answer is, maybe, but the real answer like most things I write about, is a bit more complex.  Okay, more than a bit. 🙂

First, let’s discuss the major ingredients that go into high quality joint chews for pets, glucosamine, chondroitin, MSM, and omega-3-fatty acids


All connective tissues like ligaments, tendons, and cartilage that bind the soft tissues of the body together, as well bind together the muscles and bones of the musculoskeletal system, are made of a basic building block called glycosaminoglycan.  In order for the body to make glycosaminoglycan, the body needs its major precursor, glucosamine.

Therefore, at least theoretically, and extra daily dose of glucosamine either through foods that are high in it, such as shellfish, or through supplementation with joint chews that have it on of its ingredients, should lead to a greater ability to repair damaged connective tissue structures.  In cases of arthritis, degenerative joint disease, and spinal disk disease, the major driving force behind these diseases is damaged connective tissues within these structures.  As such, glucosamine – again, at least in theory – should hold some benefit for patients suffering from these conditions.


When glucosamine is linked to a protein, it makes molecules known as proteoglycans, such as chondroitin.  With the addition of sulfur, chondroitin can be converted into chondroitin sulfate, a major component of cartilage, the tissue that pads the bones of the articulating surfaces of the joints of the body.

Physiologically, glucosamine helps the body to make more chondroitin, which when sulfated, forms the major component of cartilage.  Theoretically, more glucosamine should lead to more chondroitin sulfate, which should lead to healthier cartilage in the body.  Also theoretically, additional chondroitin in the body should also increase the structural integrity of the body’s cartilaginous surfaces.


Sulfur is a critical component to the connective tissue matrix, as it is necessary to synthesize active forms of chondroitin and glucosamine, chondroitin sulfate and glucosamine sulfate, respectively, that directly facilitate connective tissue repair.  Important dietary sources of sulfur include cabbage, onions, broccoli, garlic, radishes, and mustard.  Good luck trying to get dogs and cats to eat these food items!

Another alternative is to supplement the diet with methylsulfonylmethane, or MSM, a potent source of dietary sulfur.  Theoretically, the addition of sulfur to the aforementioned molecules increases the amount of active connective tissue repair occurring in the body.

Omega-3-fatty acids

Omega-3-fatty acids are powerful, anti-inflammatory molecules.  Omega-3-fatty acids are found in fish oils, flax seed, avocado, and different varieties of legumes.

Inflammation in the body occurs through different biochemical pathways that lead to inflammatory products.  Omega-3-fatty acids reduce inflammation in body tissues by diverting inflammatory biochemical pathways into alternative pathways that lead to inert end products that do not cause inflammation.

Omega-3-fatty acids also form a key component of the cell membranes of all of the cells that form the tissues of the body.  Therefore, diets rich in foods that contain omega-3-fatty acids or supplementation with a high quality omega-3-fatty acid isolate product, not only reduce tissue inflammation, but promote tissue repair and healthy tissue in general.

Notice I did not state “theoretically” for any of the benefits of omega-3-fatty acids.  The reason for this is that there is no jury out on the benefits of omega-3- fatty acids.  They have been proven to provide relief from arthritis, other diseases of the musculoskeletal system, and many other diseases of the body time and again in industry approved research studies.

So Why Maybe?

So if all of this sounds so great, why the “maybe” on the efficacy of joint chews in dogs and cats?  Well for one, with the exception of omega-3-fatty acids, the data on glucosamine, chondroitin, and MSM supplementation has been conflicting at best.  To date, there has not been one unbiased, industry approved study that has conclusively proven the benefit of supplementing with these compounds.

The next problem we have with these compounds is that there are many other factors that affect their result.  For example, glucosamine is made by the liver via a pathway called the glycolytic pathway, which requires the amino acid glutamine to function properly.  Therefore, a diet deficient in this amino acid will lessen the efficacy of dietary supplementation with glucosamine.

Likewise, proper levels of magnesium, vitamin B12, and vitamin B6 are essential for sulfation, the key step in the creation of glucosamine sulfate and chondroitin sulfate.  As such, a diet deficient in these nutrients would significantly lessen the efficacy of joint chews.

High Quality

You may have noted that I kept mentioning the term high quality throughout this post.  The reason I harp on this is that too many people are not aware that joint chews (and other health supplements) are not FDA regulated, thereby giving them no official watchdog that makes them prove their integrity, label claims, or even ingredients.  A few years ago, DVM News magazine published the results of a study that found that 3 out of 4 randomly chosen over the counter joint chews did not have the ingredients claimed on the labels.

In other cases, the ingredients may be there, but not in a bioavailable form that is absorbable for canines and felines, so much of what you give them exits the GI unabsorbed, and in some cases even causes GI upset.

In the case of omega-3-fatty acids, if they are not processed as pharmaceutical grade, they commonly go rancid and convert to omega-6 and omega-9 fatty acids.  Not only do these by-products not have the benefits of omega-3-fatty acids, but they rather than act as anti-inflammatory, they are actually pro-inflammatory.

To make up for this major lack of oversight in the health supplement industry, it is important to stick with pharmaceutical grade joint health supplements from companies that have other lines of pharmaceuticals on the market that make them stake their reputation on every product line they offer, including the ones that are not FDA regulated.  You veterinarian is the best source of information on which products carry the best efficacy and reputation.


While science still has yet to confirm the benefits of glucosamine, chondroitin, and MSM, under the right set of circumstances, I have seen them proven to work time and again.  By the right set of circumstances, I am referring to:

1.)    Good nutrition to support the supplement.

2.)    Selecting a pharmaceutical/veterinary grade product with proven efficacy.

3.)    Selecting a supplement that has all four of the compounds discussed in this article, not just 1, 2, or even 3 of them – all of them.

4.)    Selecting products that are rich in supporting nutrients, such as glutamine, magnesium, vitamin B2, and B12, in addition to having all the necessary joint health compounds.

5.)    Getting serious about management of mitigating factors, such as addressing underlying health concerns and obesity.

Dr. Roger Welton is the President of Maybeck Animal Hospital and CEO/Chief Editor of the veterinary information and blog online community, Web-DVM.

19 thoughts on “Everything You Need to Know About Joint Chews in Dogs and Cats

  1. My dog swallows the glycocemin instead of chewing it. Will this have a negative effect on the benefit?

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