A Promising Study of Fish Oil Fails to Test Cats Because of Their Size

A promising study about supplementing with deep-sea fish oil illustrates one of the challenges in conducting research on cats and why more research is done on dogs than cats.


A study of 77 dogs with osteoarthritis found that, when compared to a placebo, “The fish-oil treated patients improved significantly in many of the variables … indicating a true but small relief in symptoms.” Those dogs had improved in quality of life in locomotion and everyday situations, according to the report published in BMC Veterinary Research in 2012. Supplementation could be considered part of a total pain-relieving approach, especially for dogs who do not tolerate anti-inflammatory drugs, the researchers said.

The results are significant because they prove a supplement’s effectiveness using quantitative evaluation methods, says Joseph Wakshlag, DVM, at Cornell. Researchers used a force plate to measure the force dogs exerted to walk on it. They did a second study on cats, but cats didn’t weigh enough for a force-plate test and results were inconclusive. Researchers did find that taking fish oil did not harm cats — safety data that most products don’t provide.

In other tests:

From Glasgow, Scotland: A comparison of meloxicam and glucosamine chondroitin as pain control in arthritic cats over the age of 8 found that, later after a month on a placebo, the cats on glucosamine chondroitin fared better.

From the Netherlands: A small study of cats with osteoarthritis whose diets were supplemented with omega3-fatty acids had fewer symptoms. One group of cats was given fish oil with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both long-chain omega-3 fatty acids. The other group received a corn oil supplement without EPA or DHA. Owners said the cats taking fish oil with EPA and DHA were more active, climbing stairs and jumping, than those taking corn oil.

From Nestle Purina: Research found that a blend containing fish oil, B vitamins, antioxidants and the amino acid arginine helped improve cognitive dysfunction of middle-aged and senior cats. Whether the supplements given individually will provide the same improvement is unknown.

From Washington State University: A study found that fish oil and flaxseed oil can reduce skin inflammatory responses in cats, noting that flaxseed oil appears less immunosuppressive than fish oil.