Skip to Content
debunking dog nutrition myths

Veterinarian approved supplements for dogs and cats


Research into glucosamine for the treatment of arthritis in dogs, cats and humans has been ongoing for over 15 years. There is some laboratory evidence that taking a glucosamine sulfate supplement may slow down the development of arthritis in humans, dogs and cats, although the clinical impact of this effect is unclear.

Glucosamine does not appear to do anything to reverse current arthritis, nor control pain.

Conflicting research on glucosamine

There are three forms of glucosamine commonly available: N-acetyl-glucosamine, glucosamine hydrochloride, and glucosamine sulphate. Most of the supplements sold today use glucosamine hydrochloride, which is cheaper to make, but has not been proven effective.

From The Mayo Clinic: “It is believed that the sulfate moiety provides clinical benefit in the synovial fluid by strengthening cartilage and aiding glycosaminoglycan synthesis. If this hypothesis is confirmed, it would mean that only the glucosamine sulfate form is effective and non-sulfated glucosamine forms are not effective.”

Additional research suggests no additional benefit if you add ingredients to the glucosamine (MSM, chondroitin sulfate, Vitamin E, Vitamin C, shark cartilage, grape seed extract).

Finally, neither oral hyaluronic acid nor Perna Canaliculus / green lipped mussel seem to provide any additional benefit over glucosamine.

Research proving glucosamine probably doesn’t do anything useful

The 2010 GAIT study: (Glucosamine/chondroitin Arthritis Intervention Trial) – a two year human trial comparing celeboxib (a human NSAID pain reliever) with glucosamine alone, or with glucosamine/chondroitin. “Over 2 years, no treatment achieved a clinically important difference in WOMAC (Western Ontario and McMaster University Osteoarthritis Index) pain or function as compared with placebo.”

According to this very long, very expensive, and very well-received study, glucosamine appears to have no benefit in any patient population.

Dr. Magnusson, just tell me which glucosamine to buy, and how much to give!

OK fine.

I just told you that glucosamine doesn’t work.

But, if you insist…

GLUCOSAMINE DOSAGE reported in the literature and by various product manufacturers

  • Cats: 250mg daily (NOTE: it’s really hard to find a glucosamine supplement under 500mg – consider sprinkling out approximately half of a 500mg capsule each day?)
  • Dogs under 25 pounds: 500mg daily
  • Dogs 25-50 pounds: 1000mg daily
  • Dogs over 50 pounds: 1500mg daily

Recommended glucosamine brands for pets


“Glucosamine sulfate” on

“Glucosamine Sulfate” on

UC-II® – better than glucosamine??

NOT a prescription drug, but rather classified as a food ingredient derived from chicken sternum cartilage (and therefore not subject to FDA prescription drug oversight), UC-II® is a relatively new player in the arthritis game.

UC-II® consists of undenatured type II collagen, sourced and manufactured in the United States.

UC-II® Studies PDF from Vetoquinol USA

Studies have been performed using a small number of dogs (20 dogs in one study, fewer than 40 dogs in the second study), and this is a summary of their conclusions:

“Daily treatment of arthritic dogs with UC-II alone or in combination with glucosamine and chondroitin markedly alleviates arthritic-associated pain, and these supplements are well tolerated as no side effects were noted.”

Research indicates 40mg UC-II® per day is the ideal dose for most dogs with arthritis.

Where to buy UC-II®

Now Foods UC-II Joint Health by Now Foods (approx $18/60 capsules on, 40mg UC-II® per capsule)

One $0.30 human capsule contains 40mg UC-II

Omega-3 / fish oil and Omega-6 oil in dogs and cats

Photo from

There are very few supplements that veterinarians ever recommend dogs and cats take, and fish oil is often one of the good ones.

Why do dogs and cats need to eat Essential Fatty Acids? (EFA)

From Wikipedia: “Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health but cannot synthesize them. The term “essential fatty acid” refers to fatty acids required for biological processes but does not include the fats that only act as fuel.

Only two fatty acids are known to be essential for humans: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid).

Omega-6 EFA’s are found in corn, linseed, soy, canola, borage, safflower and sunflower oil, whole grains, and the body fat of poultry (chicken, turkey, duck etc.)

Omega-3 EFA’s are found in fish oil, chia, hemp, flax, and to a lesser extent, canola, soy, and walnut oils.

Coconut oil does not contain essential fatty acids

Medium-Chain or Saturated Fatty Acids are found in coconut oil and butter.

Coconut oil does not contain Omega-3 or Omega-6 essential fatty acids.

Omega-6 fatty acids for skin and coat

Your veterinarian may recommend an Omega-6 EFA supplement primarily to improve the condition of your pet’s skin and coat. If your pet’s coat is dull and dry, an Omega-6 fatty acid supplement may encourage the body’s natural production of skin oils, and keep the coat soft and silky.

Excessive supplementation of Omega-6, however, may actually be harmful, so moderation is key. Most commercial dog foods have high levels of Omega-6 fatty acids via the inclusion of animal fat in the diet, so it is rare that I find a case that truly responds to extra Omega-6 supplementation over and above what is already included in the diet.

Omega-6 dose for dogs and cats

My basic rule of thumb (and I have no science whatsoever behind this) is if you’re interested in trying an Omega-6 supplement to improve your pet’s coat, feed 1 tsp of corn oil, olive oil, canola, safflower, or sunflower oil per day, less (say, 1/2 tsp) for smaller pets, more (say, 1 tbsp) for bigger pets. REMEMBER: There are a TON of calories in oil, so decrease treats accordingly.

Omega-3 fatty acids reduce inflammation

Your veterinarian may recommend an Omega-3 EFA supplement to reduce inflammation, improve heart health, slow the progression of cancer, enhance immunity, reduce the symptoms of allergic skin disease, or reduce joint stiffness. Because most commercial diets contain lots of Omega-6, adding supplemental Omega-3’s may improve the balance of fatty acids in your pet’s diet, which may contribute to reducing oxidation and inflammation. It is very common for veterinarians to recommend Omega-3 supplementation in cases responsive to anti-inflammatories.

Omega-3 dose for dogs and cats

Omega-3 fatty acid capsules (fish oil) are labelled with their guaranteed content of EPA and DHA, which are basically the active ingredients in fish oil.

To start, feed your average-to-larger sized dog one or two human-sized fish oil capsule per day, containing a total of at least 200mg each of EPA and DHA. Most people find it easiest to cut a hole in the top of the capsule with scissors and squirt it on the food. Feed your tiny dog or your cat a half-human-dose (usually 1/4-1/2 tsp) of Salmon oil or flaxseed oil, if that’s easier to find in bottles.

Best of health to you and your furry family members, from Leo’s Pet Care!

Thanks for sharing this article with your pet-loving friends!

Back to top