Chris Vanderhoof, DVM, MPH
Glucosamine and Chondroitin have been recommended by veterinarians for decades to aid in the slowing of the development of osteoarthritis and to lessen symptoms in pets already affected.
But how do these two supplements work, when do we use them, and more importantly, how much do you provide a cat or dog on a regular basis?
In this article we’re going to answer these questions so that you have a good starting point to help address joint health in your dog and to have further discussions with your veterinarian about the topic.
A Little About the Joint
To understand what glucosamine and chondroitin are and how supplementing them in the diet can be helpful, we first have to understand just a little about the joints and joint fluid. Don’t worry, this won’t be a super in-depth anatomy and chemistry lesson, just some basics.
The whole purpose of joint fluid, also called synovial fluid, is to lubricate the joints and make sure the the bones making up the joint, like your humerus, radius, and ulna at the elbow joint for example, don’t grind on each other.
Cartilage covers the ends of bones and also provides cushion, but synovial fluid provides most of the nutrition to keep cartilage healthy. Without healthy joint fluid, cartilage can become diseased and damaged. When cartilage is damaged, the joint is not well lubricated, and bone on bone grinding occurs, leading to severe arthritis. This is what we’re looking to slow down or prevent.
Joint fluid is made up of compounds called glycosaminoglycans. This word is definitely a mouthful, but remember it because these compounds are vitally important. They are what makes the synovial fluid thick, viscous and functional as a lubricant and shock absorber for the joints.
What is Glucosamine?
Glucosamine is a natural compound found in joint cartilage. Cartilage cells use glucosamine to produce those glycosaminoglycans and keep the joint fluid healthy. Which in turn keeps the cartilage healthy.
Glucosamine also has a couple more functions. It regulates the production of collagen and proteoglycans, the two main components that make cartilage what it is. It also has some mild anti-inflammatory effects as a free radical scavenger.
What’s a free radical scavenger? To know this, you need to know what a free radical is first.
An oxygen molecule is made up of a pair of oxygen atoms. When oxygen molecules split in half, these single atoms have an extra electron in their outer shell. This “lonely” electron makes that atom behave in a very needy manner, desperately trying to find other things to bind to. These aberrant atoms are called free radicals, and their needy binding behavior causes a lot of damage to cells in the body. This is called oxidative damage or oxidative stress.
A free radical scavenger has the ability to bind and essentially deactivate these harmful free radicals. Free radical scavengers that can bind to those lonely oxygen atoms are called antioxidants.
By acting as a free radical scavenger, glucosamine can reduce inflammation and damage in the joints and throughout the rest of the body.
What is Chondroitin?
Along with hyaluronic acid and a few other compounds, chondroitin is one of those actual glycosaminoglycans.
Found within cartilage, chondroitin is the main structural component that makes cartilage a good shock absorber and provides most of its resistance to compressive forces.
Chondroitin also helps to inhibit destructive enzymes within cartilage and joint fluid, helping to prevent arthritic changes. It also stimulates further production of glycosaminoglycans like itself, as well as those proteoglycans that are the main filler components within the latticework of cartilage.
When Do We Use Them?
As you can see, glucosamine and chondroitin are pretty vital to our pets’ joints (and our own as well!). So it stands to reason that supplementing them in the diet could provide joint health benefits.
So in what circumstances is it best to start a glucosamine/chondroitin supplement? This all largely depends on our risk for joint disease. We’ll discuss three scenarios that can help highlight when to consider using them.
Scenario 1: The Puppy
Let’s say we have an 8 month-old large breed puppy who starts to show signs of limping after playing. When his parents bring him in to the vet and x-rays are done, early signs of hip dysplasia are seen.
In this early phase of hip dysplasia, the hip joint has a lot of laxity from a young dog’s tendons and ligaments being very elastic. This leads to the head of the femur, the “ball” of the ball and socket joint, subluxating or popping in and out with movement. This phase tends to improve by one year of age as everything tightens up with growth and we may actually see the limping improve on its own for some time.
However, we also know that the structural deformity of hip dysplasia will never go away and that over time, our young puppy is going to develop arthritis at an earlier age than most other dogs. Thus, we would consider starting this puppy on a glucosamine/chondroitin supplement like Joint Health as soon as possible as a preventative to help slow this process down.
This scenario could also apply to any young cat or dog that sustained a traumatic fracture, a deformity in bone growth, or a problem with proper development of one or more growth plates in bones. Really anything that can lead to arthritis later in life.
There are also other developmental diseases that affected pups are born with other than hip dysplasia, including elbow dysplasia, osteochondritis dissecans (an inflammatory and degenerative disease of cartilage), and patellar luxation (when the kneecaps pop in and out), that can lead to chronic inflammation and pain that worsens with age.
Scenario 2: The Older Dog
Now let’s say we have a 10 year old large breed dog. She’s a bit overweight, and could stand to lose about 10lb. Her parents brought her in to the vet because they’ve noticed that she has started to have more difficulty standing up with her hind legs after she’s been laying down or sleeping.
Taking some x-rays shows that she has normal-looking hip structure, but there are signs of arthritis around the hips, knees, and some other joints in the legs as well.
According to the American Animal Hospital Association (AAHA), at least 20% of dogs in the United States suffer from osteoarthritis. That’s 1 in 5 pups. And this is probably an under-represented number, since many dogs can hide mild signs of arthritis for a long time.
Osteoarthritis classically presents as an initial discomfort in the joints that seems to improve after a pet starts to get moving and “works out of it”. You might see this after you wake up your older pup from a nap to get going for a walk. The initial getting up part is hard, but once he gets going on the walk, everything seems fine.
We can also see signs of arthritis in pets that start to have difficulty with stairs, especially going down the stairs.
This particular dog was mentioned as being overweight on purpose to help highlight how important it is for joint health to keep our pets at a good, slim body condition. In this dog’s case, the extra weight has probably led to worsening signs of arthritis earlier in life.
If you feel like you’re seeing some signs of arthritis in your older dog (or even a younger dog that had some kind of predisposing injury or growth issue) starting a glucosamine/chondroitin supplement can both help to provide some relief as well as slow down the degenerative inflammatory process of arthritis.
Scenario 3: The Older Kitty
Our last scenario focuses on our feline friends. A 10-year old cat comes into the vet just for a wellness exam. There’s no complaints from the parents, but when examining this kitty’s joints, the doctor notes some discomfort in the elbows and hips and suspects arthritis.
This scenario highlights the importance of realizing that cats have arthritis too. There was actually a time a few decades ago, when veterinarians didn’t think arthritis really affected cats and that they had some kind of natural mechanism as a barrier against it.
But according to AAHA, as few as 40-50% of cats have osteoarthritis and one study even quoted up to 90%. So cats may actually be more prone to developing arthritis than dogs, but it just turns out they’re just much better at hiding it.
In any cat that’s reached senior age status (around 7-10 years), starting a glucosamine/chondroitin supplement is a great idea, since we know a lot of felines develop arthritis and can be in discomfort from it, even if they show few signs of it. We may not be walking cats everyday, and they do sleep a good portion of the time. But for all their lax behavior, their extreme agility, jumping, and running ability can catch up with them.
Hopefully these scenarios helped to illustrate when starting a glucosamine and chondroitin supplement may be best. But since we can’t go over every specific situation, here’s a general guideline to think about: use it in our older pets who are more prone to arthritis, and in our younger pets if they’ve suffered from a condition that predisposes them to arthritis later on. If you’re not sure one way or the other, make sure to check in with your pup or kitty’s doc.
How Much Do We Use?
Determining how much glucosamine and chondroitin to use can be a challenge due to a couple of barriers, but we’ll look to provide some guidelines. These barriers stem from three main areas.
The first is that glucosamine and chondroitin aren’t drugs, they’re supplements. This means that they have never been through the same type of rigorous dosage and efficacy studies that drugs and medications are required to pass, and there are no requirements for FDA approval prior to release.
The second barrier is that since glucosamine and chondroitin are not considered drugs and have no FDA approval, there is a lot of variability from product to product, making comparisons and evaluating efficacy difficult.
The third barrier is that there is very little published scientific evidence proving that glucosamine and chondroitin work. And in the same vein, there’s little published data to support a specific dosage. One study from 2007 published in The Veterinary Journal did show a statistically significant improvement in dogs with arthritis, though it did take a little over two months.
That being said, veterinarians have been recommending glucosamine and chondroitin supplements for many years, which means there must be something beneficial to their use. We have what we call “anecdotal” evidence, meaning that while there may not be hard statistical data, we see the results and clinical improvements in our patients, and have for a long time. I recall firsthand seeing our 12 year old family cat’s mobility noticeably improving after a couple weeks of adding a glucosamine supplement to his food.
This long amount of time of recommendation and use has led to some established guidelines for dosing.
The general dosing recommendation is to start at 15-30 milligrams per kilogram per day. For an average 10lb cat, this equates to about 150 to 300mg. For a 30lb dog, this is about 200-400mg and for a 80lb dog, about 550 to 1000mg.
Anecdotal reports have also suggested to start with a higher dose initially where you essentially double the above doses. After about 4-6 weeks, if a positive response is seen, the dose can be decreased in half (to the doses provided above) or given every other day.
Fortunately, glucosamine and chondroitin have a very large safety threshold, so some tweaking at the advisement of your veterinarian to see what works best, can be considered. For example, doubling the dosage during times of recovery from an injury for several weeks may be appropriate.
How Do I Choose a Product?
Glucosamine and chondroitin supplements have been in use for a long time. So how do you choose which product is best for your pup or kitty?
Use a Product Made for Pets
You can at least narrow down your search a little by using a product made with pets in mind. Forms made for pets are usually easier to administer and more palatable. Many come either in a powdered form that’s easy to mix with canned or moist food, or in tasty chewable tablets.
And while quality control is still always a concern as we’ll talk about in just a second, pet supplements are less likely to contain harmful artificial sweeteners like xylitol, or other concerning ingredients like garlic.
As we already talked about, glucosamine and chondroitin aren’t considered drugs, so FDA approval is not required for their release in a product form. This means that there is a lot of variability among products, including dosages, concentrations, and dosing recommendations.
But while there is no legally required approval of these products prior to release, some companies, like Healthy Solutions for Pets, voluntarily choose to adhere to stricter quality control measures.
The National Animal Supplement Council (NASC) (https://nasc.cc/nasc-seal/) is a non-profit group consisting of members of the pet supplement industry that strive to maintain standards and strict levels of quality assurance with their products.
The NASC Quality Seal can only be displayed on products of companies that have voluntarily met several requirements
- Have a quality control manual in place that ensures a consistent and quality product
- Have an adverse event reporting system in place
- Comply with very strict labeling guidelines for all products
- Provide warning or cautionary statements on labels as recommended by the FDA Center for Veterinary Medicine
- Submit to random 3rd party audits by an independent lab to ensure that product ingredients meet label claims
So when looking for any supplement for your pet, make sure to look for a product like Joint Health that displays the NASC Quality Seal, as this is the best standard in the pet supplement industry to provide a safe and quality product that matches its claims.
Lastly, look for products manufactured in the United States. While this does not guarantee safety 100%, there have been far more concerns with products manufactured overseas, especially in Asia, in regards to contaminants or toxic materials finding their way into products.
You may have figured that since glucosamine and chondroitin are both natural compounds, that the supplements must be sourced from natural, animal sources. Thus, it can be an important consideration as a consumer to know where these products come from.
Most glucosamine can actually be sourced from shellfish or from synthetic sources. If derived from shellfish, make sure that these are farmed, sustainable sources.
Chondroitin can come from several sources, but primarily bovine (cows) and porcine (pigs) sources are used for most products. Shark cartilage sources may be used for some products, but consider avoiding these. While cows and pigs are technically sustainable sources, overfishing of sharks has become a significant global concern, with several species on the endangered list.
Ask Your Veterinarian
Because use of glucosamine and chondroitin by veterinarians is based largely on anecdotal evidence that they work, it’s a really good idea to discuss with your pup or kitty’s doc which products he or she feels would work best for your furry friend and what dosage they would suggest starting with.
It Can’t Hurt, So Try It
There’s a motto in veterinary medicine that all vet professionals strive to live by, which is “do no harm”. Although the dosing for glucosamine and chondroitin can be a little uncertain and not every pet may see benefit, we do know that the safety threshold is very high and adverse effects are very rare.
So while there’s no guarantee that these products will make a huge difference, especially with severe disease, glucosamine and chondroitin are very safe products to use, so trying one out after discussing with your vet can’t hurt.
As with many supplements, keep your expectations with glucosamine and chondroitin realistic. Glucosamine and chondroitin are supplements, not medications, meaning they should be included as just one part of an anti-inflammatory and pain therapy regimen.
While the one study that was mentioned did see a positive response with these supplements, the response time and pain relief they provided paled in comparison to non-steroidal anti-inflammatory drug use.
NSAIDs are still the mainstay of our battle against arthritis in dogs, as long as a pup’s body tolerates them. For cats unfortunately, we don’t have good long-term anti-inflammatory options, perhaps making glucosamine/chondroitin even more important for our kitties.
Finally, expect results to take some time. The average time frame to response is about 4-6 weeks. The dogs in the referenced study were assessed at two months.
But as far as joint supplements go, these two natural components have been trusted for decades to assist with degenerative joint diseases and good quality products are extremely safe to use. So in essence, chat with your vet about starting a glucosamine/chondroitin supplement--it can’t hurt!