What is it?
Osteoarthritis (OA), also called degenerative joint disease (DJD), is a common and painful disease in older humans and animals. OA mostly affects cartilage, the hard but slippery tissue that covers the ends of bones where they meet to form a joint. Healthy cartilage allows bones to glide over one another with little friction. It also absorbs energy from the shock of physical movement.
In osteoarthritis, the surface layer of cartilage breaks down and wears away, exposing the underlying bone. Bone rubbing against bone causes pain, and leads to inflammation, a complex response which contributes to further cartilage loss and discomfort. Over time, small deposits of bone – called osteophytes or bone spurs – may grow on the edges of the joint. Bits of bone or cartilage can break off and float inside the joint space. This causes more still more pain and damage.
Because animals cannot directly inform their caretakers of mild discomfort, the first signs of OA in veterinary patients are usually lameness and a reluctance to engage in normal activities. By the time such signs are noticed, the condition has usually progressed to moderate or severe disease. A diagnosis of OA usually requires a physical examination by a veterinarian, who can identify subtle signs of pain, osteophytes, and reduced range of joint motion. X-rays can also help identify DJD, though these are not always reliable indicators of discomfort or function.
The primary treatments for humans and animals with OA are weight loss, regular moderate exercise, and pain medications, typically the non-steroidal anti-inflammatory drugs (NSAIDs). There has also been interest among some health care providers in so-called nutraceuticals- substances derived from food sources that might treat the symptoms or alter the progression of OA.
Glucosamine is a substance found in joint cartilage and joint fluid. It is normally produced by the body from basic ingredients in food, and some is incorporated into joints. Though glucosamine is only one of the many building blocks of cartilage, it has been theorized that supplementing glucosamine orally might stimulate production or repair of cartilage. Some researchers have also suggested glucosamine might reduce inflammation in arthritic joints and thus reduce discomfort and slow the progression of the disease. Most supplement forms of glucosamine are derived from shellfish.
Chondroitin sulfate is another normal constituent of cartilage, and it has also been theorized to reduce inflammation and cartilage degradation in OA and perhaps to slow progression and improve comfort. Chondroitin in supplements is usually derived from cow cartilage.
Since glucosamine and chondroitin are categorized as nutritional supplements, they are not regulated by the Food and Drug Administration. Manufacturers do not have to prove that they are safe or effective in treating OA, and they do not have to abide by the strict quality control requirements for the production of approved drugs. Independent testing of over-the-counter glucosamine and chondroitin products have shown that they vary greatly in composition, and many do not actually contain the ingredients indicated on the label. Therefore, even if the substances have a role in treatment of OA, there is some concern that the actual preparations sold for humans and animals may not be of any value simply because they may not contain much of the ingredients.
Does It Work?
There has been a great deal of research on the effects of glucosamine and chondroitin on cells from joint tissues isolated in the laboratory. Though the results are inconsistent, some studies do show a number of actions on cells that might suggest a use for these agents in patients with OA, so the theory behind their use is plausible. However, there are other reasons for questioning whether these agents could actually work in a real patient.
For example, some controversy about whether oral preparations of chondroitin sulfate, which is a very large and electrically charged molecule, can be absorbed into the body and whether it actually get into joints affected with OA. Results of studies on the availability of oral glucosamine and chondroitin are extremely inconsistent, but generally show a low level of absorption in humans, rats, dogs, and horses. While some of the absorbed molecules do appear to reach affected joints, it is not clear if the amount is sufficient to have any effects. The amount that reaches the joints when the products are given orally is generally less than the amount used in the laboratory to demonstrate possibly useful actions on isolated cells and much less than the amount of glucosamine already circulating in the animal’s body.
Extensive clinical trials have been conducted in humans to determine if glucosamine and chondroitin can reduce symptoms or slow progression of OA. The best quality scientific studies require blinding, where the patients and researchers do not know whether each subject is getting the real treatment or a fake (placebo) treatment. And many other factors complicate interpretation of human clinical trials, so confidence in the results can only come from consistent, repeatable outcomes of numerous well-designed trials conducted by different investigators.
The results of these clinical trials are also highly inconsistent. In general, older studies with small numbers of patients and funded by supplement manufacturers showed some benefit from oral glucosamine and chondroitin. However, as larger, independently-funded trials with more subjects and better design have been published, the evidence has become predominantly negative.
The largest and best trial so far is the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), a study comparing glucosamine and chondroitin, separately and together, against placebo and an NSAID (celecoxib, or Celebrex). Overall, the NSAID improved comfort and function significantly more than the placebo, while the various glucosamine and chondroitin products did not. Another study of many of the same subjects over 2 years did not find any significant difference in loss of joint space on x-rays (a measure of progression of OA) compared to the placebo. On balance, then, the evidence in humans suggests little to no benefit of these agents on symptoms or progression of OA.
There is very little research on the use of glucosamine and chondroitin in OA for veterinary patients. A recent review found only one good quality study comparing a combination glucosmine/chondroitin product to NSAIDs and placebo in dogs. In this study, the NSAIDs showed significant benefit on both objective and subjective measures of pain compared with placebo, but there was no difference between the placebo and the nutraceutical product.
Therefore, though there are some interesting effects of chondroitin and glucosamine on joint tissue in the lab, there are also questions about whether they could be effective in real patients. The balance of the clinical research evidence in both humans and animals does not suggest there is any real benefit of oral supplementation of these agents in patients with osteoarthritis.
Is It Safe?
Oral glucosamine and chondroitin supplements appear to be safe. There is some possibility that they may interfere with platelets, an element in the process of blood clotting. Alone, this does not seem to be of any clinical significance, but it is recommended that they not be used in patients already on anti-coagulant medications such as aspirin, clopidogrel (Plavix), or heparin.
There are also some concerns about glucosamine interfering with treatment for diabetes since it is structurally similar to sugar. In humans, this does not appear to be a real risk for diabetic patients. There is no research on this issue in veterinary patients.
Ø Glucosamine and chondroitin appear to have effects on joint tissues isolated in the laboratory that might indicate they could be useful adjuncts to osteoarthritis treatment if these effects also occurred in patients given oral preparations of these substances. However, there are reasons to question whether they could have such effects because they are poorly absorbed, and little of what is taken orally actually reaches affected joints.
Ø In humans, the largest and best clinical trials studying oral glucosamine and chondroitin supplements shows little to no effect on pain or on the degeneration of cartilage in patients with osteoarthritis.
Ø There is virtually no good quality research on the use of glucosamine and chondroitin in veterinary patients. The best study so far, done in dogs, found a combination of these agents to be of no benefit for patients with osteoarthritis. Further research in animals with osteoarthritis is warranted, but at this time the evidence does not support the use of glucosamine and chondroitin in these patients.
Ø Glucosamine and chondroitin taken orally appear to be safe in veterinary patients. However, they should not be taken by patients on anti-coagulant medications, and they should be used with caution in diabetics.
Ø The best treatments for osteoarthritis in veterinary patients, as in humans, are maintenance of a healthy weight, regular moderate exercise, and non-steroidal anti-inflammatory medications for pain
References and More Information
Aragon, C.L., Hofmeister, E.H., Budsberg, S.C., Systematic review of clinical trials of treatments for osteoarthritis in dogs. J Am Vet Med Assoc 2007; Feb 15;230(4):514-21.
Barker Bausell, R., Snake Oil Science: The Truth About Complementary and Alternative Medicine, Oxford University Press, 2007
Clegg, D.O., et al. Glucosamine, Chondroitin Sulfate, and the Two in Combination for Painful Knee Osteoarthritis. N Engl J Med. 2006 Feb; 23;354(8):795-808.
Goggs, R., et al. Nutraceutical Therapies for Degenerative Joint Diseases:
A Critical Review. Crit Rev Food Sci Nutr 2005;45:145–164
Moreau, M., et al. Clinical evaluation of a nutraceutical, carprofen, and meloxicam for the treatment of dogs with osteoarthritis. Vet Rec 2003; 152:323-329
National Institute of Health, National Institute of Arthritis and Musculoskeletal and Skin Diseases. Handout on Health: Osteoarthritis 2006. http://www.niams.nih.gov/Health_Info/Osteoarthritis/osteoarthritis_hoh.pdf
Neil, K.M., Caron, J.P., Orth, M.W. The role of glucosamine and chondroitin sulfate in treatment for and prevention of osteoarthritis in animals. JAVMA Apr 2005;226(7);1079-1088
Sawitzke, A.D. The effect of glucosamine and/or chondroitin sulfate on the progression of knee osteoarthritis: A report from the glucosamine/chondroitin arthritis intervention trial. Arthritis Rheum 2008 Oct;58(10):3183-91
The Cochrane Collaboration, The Cochrane Reviews, a searchable database of systematic reviews of the human medical literature at http://www.cochrane.org/reviews/
© Brennen McKenzie, 2008
Thanks! I put a lot of time and effort into researching and writing these reviews, so it’s nice to hear they’re helpful to someone. 🙂
Today at the vet’s office I saw on their TV (one of those ads only TVs from drug reps–I assume) a glucosamine product was being heavily marketed. I found this very distasteful on several levels, but mostly because I suspected that this stuff is fairly useless. Your entry has verified my suspicions and I am grateful to you for this post.
The question is: Should I let my vet know how I feel about this, or just look for a new vet? Is it now necessary to interview a vet to weed out the woo-friendly?
Unfortunately, I know a lot of very good veterinarians who subscribe to some pretty ridiculous practices. Glucosamine is widely accepted as safe (which it probably is) and effective (which it probably isn’t) by most mainstream veterinarians. So I wouldn’t necessarily give up on your vet just because they use glucosamine.
The woo-factor has a scale of degrees. I would certainly avoid a vet who marketed temselves as “holistic” or whose practice consisted primarily of CAM practices, and certainly if they promoted some of the clearly erroneous cliches about evil vaccines, toxic pet foods, and so on. I would probably avoid one who made extensive use of CAM therapies alongside of conventional ones simply because this suggests they don’t have very strong skill or interest in critical evaluation of their practices and just go with whatever sounds good.
But if you have a good relationship and good communication with your doctor, and if their approach seems generally sound, I would absolutely feel free to let them know that you personally don’t care to experiment with unproven therapies, that you prefer things validated by reasonable evidence, and that if they want to offer something unconventional for your pet you’re open-minded but you like them to be able to produce some reasonable evidence that it is safe and works, beyond just gut feelings or anecdotes.
Most of us in practice are accustomed to accomodating our recommendations to the values and beliefs of our clients to whatever extent we can without compromising what we believe are important principles of ethics or good medicine. If my clients ask me about CAM, for example, I give them my opinion and the evidence I have and let them know if it’s something I’m not willing to provide, and then I give them the card of a local holistic vet who will offer what they want if they still want it after they’ve heard my take on it. They way I look at it is that the client is paying for my advice, but they aren’t obligated to take it.
I would hope holistic and CAM vets could do the same, but I will say that they seem to be a bit more evangelical about their practices and inclined to try harder to force clients to do things their way, though this is a generalization based on personal experience and may very well not be true of the majority.
I have added a section to my advanced directive for health care for myself clearly stating that I do not wish to be treated with CAM methods without my express consent, and I always talk amiably with my doctors about what I will or will not accept, but I don’t necessarily give up on a doctor that may offer me something woo-ish I don’t trust, as long as I think they are otherwise smart and sound clinicians and they are willing to respect my wishes on the subject.
I hope this helps!
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Thanks so much, SkeptVet. Although it was as bit difficult to find your review (by googling “chondroitin glucosamin for dog works?”, it came only after the 3rd page!), it was totally worth it. Excellent review, balanced arguments, and the papers to back it up.
I have a young German Shepherd Dog that has confirmed hip dysplasia, and the vets I saw by the time that diagnosis was made were very firm in their belief that Glucosamine+Chondroitin really works. They all said that I should give G+C to my dog in order to postpone the development of arthritis, and later on, to treat the symptoms. Sadly, this is yet another popular legend.
I am sorry to see so many vets caving in to that sort of pseudo-science. Not only that: increasing numbers of elderly people are now taking G+C, based on supposed “evidence” from vets!
I hope more people find their way to you article, and take this issue more seriously.
Thanks a lot for your hard work doing this article!
Glad you found it helpful! I would quibble that the woo runs the other direction, with the veterinary market for glucosamine following the widespread use among humans. Either way, though, I have a hard time convincing my colleagues (or my own doctor) that no matter how many anecdotes they collect for how helpful it is, it really is just a placebo. Not a big problem for people, since if they think they feel better, then in some sense they really do. But a real shame for my patients, who’s owners may avoid truly effective treatments if they, or their vets, believe the glucosamine is helping when it isn’t. 🙁
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Hey There Skeptvet,
Maybe a little off topic, however, Hey all,
My question is regarding the use of human-quality Glucosamine and Chondroitin supplements in large dogs. My dog (a Lab) has developed hip dysplasia and he is currently being treated with Cartrophin injections (which I’ve been told is like an anti-inflammatory for joint diseases), but this medication is costing me an absolute fortune.
I know that Glucosamine and Chondroitin have both been extensively studied and have been found safe and effective in osteoarthritis and degenerative joint disease in humans, but I was wondering if anyone knew whether or not it would be safe to use in my dog.
Of course, I want to do what’s best for him (and I’m happy to keep paying for his veterinary bills if I have to) but I thought there wouldn’t be any harm in asking about this if it could potentially save me some money.
Thanks guys, I look forward to your answers!
If you see the section about glucosmaine in my review of canine arthritis treatments, you’ll see that the evidence pretty clearly suggests that glucosamine is safe and is NOT effective. The evidence for humans also suggests little to no benefit. It is harmless but probably a waste of money and certainly no substitute for NSAIDs, which are a proven treatment for arthritis pain. Of course, since the web site you link too sells glucosamine, I don’t expect you to actually care about this.
A lot of other folks shall be benefited from your writing.
Hi, out of interest, were you not aware of the 2007 paper published in The Veterinary Journal comparing a Glucosamine/Chondroitin formulation to carprofen in dogs with arthritis when you wrote this – as you haven’t mentioned it?
Also out of interest, did you read the full GAIT trial paper or just the abstract? I was wondering this because you mention that Glucosamine/Chondroitin did not improve function and comfort, however you left out the part in the paper where it explains that for the moderate/severe patients the Glu/CS improvement was significantly better that both the placebo *and* the NSAID?
I found it interesting that the dogs in the 2007 paper and the people in the GAIT trial that showed an improvement after using Glu/CS, were *both* moderate/severe – which is consistent.
I presume you’re talking about this paper?
McCarthy G, O’Donovan J, Jones, B, et al. Randomized double-blind, positive-controlled trial to assess the efficacy of glucosamine/chondroitin sulfate for the treatment of dogs with osteoarthritis. Vet J 2007;174:54-61.
This paper, and the one other controlled clinical trial of glucosamine in dogs, were reviews here:
McKenzie, BA. What’s the Evidence? Glucosamine and chondroitin for canine osteoarthritis. J Amer Vet Med Assoc. 2010;237(12):1382-3.
This review illustrates a number of the limitations of the McCarthy study:
The other clinical trial involving dogs had fewer limitations and was definitively negative:
Moreau M, Dupuis J, Bonneau NH, Desnoyers M. Clinical evaluation of a nutraceutical, carprofen and meloxicam for the treatment of dogs with osteoarthritis. Vet Rec 2003;152:323-329.
On balance, then the evidence is inconsistent and overall more negative than positive.
As for the GAIT trial, the main outcome showed no benefit. When a subgroup analysis was done, benefit was shown for some patients. Unfortunately, such post-hoc subgroup analyses are a common way to generate an apparently positive result when the main thing you start out intending to evaluate doesn’t work out. Additional studies in which only patients in the moderate/severe category are evaluated would be needed to validate this kind of “after-the-fact” statistical analysis.
So again, the majority of the evidence is negative, and the fewer limitations and caveats there are in a trial, the less likely there is to be a significant effect found. On balance, there isn’t much reason to believe glucosamine has a clinically significant benefit for most patients. Even if it turns out to have a marginal benefit for some patients, that hardly justifies the widespread use of it or the enormous amount of money currently spent on it.
Just finished reading Skeptvet’s report on glucosamine/chondroitin but after I ordered “Flexwize” (U.K. product) liquid glucosamine/chondroitin (!!!! My 10 yr old labrador is starting to slow down and looks very stiff in the mornings so I am willing to give it a try. According to your report, it will probably make no difference my dog’s arthritic condition but might it not help his general wellbeing . . . all those natural “healthy” components? As part of balanced diet, might it help to extend his life expectancy? Besides I have read that NSAIDs can lead to kidney failure and that killed my previous dog … he suffered with it and I don’t want that to happen to this dog. Thank you.
There is no reason to think glucosamine will help with anything, though it is also probably harmless. And it is very likely that you will see what looks like improvement after you start using it simply because almost half of vets and owners report improvement of arthritis symtpom even when they are unknowing giving a fake, placebo treatment. We are simply inclined to hope for, and thus to see, the best whatever we do. The only problem with that is if this mistaken perception leads us to believe we are treating our pets’ pain when we actually aren’t. My only objection to glucosamine is that it is probably useless but it leads us to feel like we are doing something, and as a result we often don’t give our pets the real pain relief they need.
As for other vague “healthy” ingredients, that really isn’t how the body works. Specific substances have specific effects, and if these haven’t been demonstrated by any kind of scientific study, we have no reason to think they are there. The issue is a very big subject in human medicine now as more and more studies are showing that the widespread practice of healthy people taking multivitamin supplements is almost always useless and sometimes even causes harm. So I don’t see any reason other than wishful thinking to believe your pup will get anything out of this supplement.
As for NSAIDs, the risks and the benefits are both proven, and it is a question of balancing these. The evidence shows that if properly used and monitored, these are very effective at treating arthritis pain and very safe. While nothing that actually does anything at all is completely without risks, my concern is that peopel with arthritis are in pain, and it is almost certain that dogs with arthritis are in pain too. Since it seems clear that glucosamine is safe but probably useless, and NSAIDs are low-risk and very effective, I hate to see us avoid treating our pets’ pain with real medication out of fear. It’s true, sometimes bad things happen. But the vast majority of the time, the benefit outweighs the risk.
Only you can decide what to do for your pet. For my own dog, who recently passed away at 16 years old, and who suffered from hip dysplasia, elbow dysplasia, and a ruptured cruciate ligament, I kept him comfortable with a variety of treatments, including NSAIDs, for many years. As a mere anecdote, of course this doesn’t prove anything about the therapies I used, but it does illustrate that I mean what I say, which is that I think using these medicine is in the best interest of our pets when they are used properly.
Thank you so much for this excellent summary based on SCIENCE.
I wonder if there is any point to using other nutritional formulations to help with arthritis? I happened on this product when looking to reorder some chondritin for my elderly big dog: [link to purelife4pets removed] The claim is made that this product containing elastin, collagen, etc can mitigate arthritis where the chondritin/glucosamine supplements do not. But the website is pretty uninformative over all on ingredients.
I also happened on this blog, so should say thanks for the sensible summary of the evidence on these supplements. They appear to be placebos for the owners.
Yes, the classic claim that “scientific studies show….” without any actual published study. There is nothing new offered on this site to suuggest the product is any different from all the other joint supplements out there or that any new evidence is available.
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has there been any recent studies on this as im now willing to try anything ( I know I know ) as my girls Poppy is still easily made lame due to elbow dysplasia , we have had Arthramid injections into the joint that didnt appear to help at all , and now she is 10 weeks into a 12 week program of NSAIDS which help but not enough for healthy happy life. You posted above ” I kept him comfortable with a variety of treatments, including NSAIDs, for many years.” , may i ask what these other treatment are so i can find out if they are suitable for Poppy .As ever many thanks for this invaluable blogg .
Anyone ? , is the verdict on this still out or do we now know it to either work or not ?
The trials over. They have given the lethal injection. And those quacks still selling it on death row still say they believe it works because they have seen it work.
Thank you Art , ill stick with the NSAIDs so long as they dong start causing issues of their own .
Thank you so much for the information! I’ve been looking for joints supplements for my senior dogs and I’m glad I did not make an impulse purchase:)
I’m wondering by any chance have you heard of a product called Antinol/Lyprinol/PCSO524? It claims to be the active component of New Zealand green-lipped mussels, there are even a few clinical research that look legit. I do not have a medical nor a statistical background so it is very likely that I missed something critical while trying to interprate these papers. It would be wonderful if you can give some insights on this!
this seems to be a promising trail, at least for human
The study is interesting, but of course it is also typical of the small studies that often show interesting results but aren’t replicated or confirmed. It is odd that they used only fish oil as a comparison, since that has a relatively small effect on OA pain. A placebo an/or an NSAID as a comparator would have made a much more convincing study. A more recent study
used an NSAID as a comparator and found some effect on weight bearing though no obvious benefit in terms of pain. All-in-all, interesting but still very preliminary data.
Thanks for sharing!