Two controlled clinical trials find that fish-derived omega-3s provide substantial relief and benefit to dogs with arthritis
by Craig Weatherby
When people say “arthritis” they usually mean osteoarthritis.
It's the most common type of arthritis by far, and distinct from the relatively rare autoimmune disease called rheumatoid arthritis.
Osteoarthritis is associated with normal aging and with extraordinary joint stresses… such as those experienced by construction and other workers who kneel on hard surfaces.
Of course, dogs get osteoarthritis as well, and probably suffer as much discomfort as people do.
Aspirin and other non-prescription remedies for the pain of human arthritis work pretty well, but come with the risk of serious adverse effects, including death from silent gastric bleeding.
Humans and canines take different arthritis drugs… but the canine ones also come with risks of adverse side effects. These include vomiting, loss of appetite, depression, lethargy, and diarrhea… and can include the serious side effects seen with human arthritis aids, such as gastric bleeding, ulcers, and kidney or liver problems.
According to the Arthritis Foundation, glucosamine and chondroitin supplements are safe and have shown benefit in dog studies… as have omega-3 fish oils5.
And now—confirming the indications from previous studies1,2—fish oil has proved itself to be an effective arthritis remedy in two randomized, double-blind, controlled clinical trials from Kansas State University's College of Veterinary Medicine.
Study #1: Effects of omega-3s on weight bearing ability
The first clinical trial tested the effects of omega-3 fish oil on arthritic dogs' ability to bear their own weight without signs of lameness or pain3.
The owners of 38 privately owned dogs volunteered their arthritic canine pets for the three-month-long trial.
Among these dogs, 16 received a control diet of standard dog chow, and 22 received a test diet of the same chow plus fish oil, which constituted 3.5 percent of the food by weight… a pretty hefty dose.
The investigators conducted periodic orthopedic evaluations and “force-plate” analyses of the most severely arthritic limb of each dog.
Additionally, the dogs' owners completed questionnaires to report and characterize any changes in their pets' arthritis symptoms.
After 90 days, the fish oil group showed a significant 5.4 percent improvement in weight-bearing ability, compared with 0.4 percent in the control group (i.e., less than one-tenth as much improvement).
Improvement in a measure called “peak vertical force” was evident in 82 percent of the dogs in the test-food group, compared with 38 percent of the dogs in the control-food group.
In addition, according to investigators' subjective evaluations, dogs fed the test food had significant improvements in lameness and weight-bearing by the last day, compared with measurements obtained on day one.
The Kansas team penned this conclusion: “At least in the short term, dietary supplementation with fish oil omega-3 fatty acids resulted in an improvement in weight-bearing in dogs with osteoarthritis.”3
Study #2: Effects of omega-3s on rising, walking, playing
The second clinical trial was designed to assess the effect of food enriched with omega-3s from fish oil on clinical signs of osteoarthritis in dogs4.
The test diet had much more omega-3s and much less pro-inflammatory omega-6 fat than is usual for dog chow.
This is significant because omega-3s are generally anti-inflammatory, while omega-6 fatty acids are generally pro-inflammatory.
The study involved 127 pet dogs with arthritis in one or more joints. They were assigned to be fed one of two diets for six months:
The dog owners completed a questionnaire about their pet's arthritis symptoms, and investigators performed a physical examination and collected blood samples to test at the onset of the study and at six, 12, and 24 weeks afterward.
- Typical commercial dog food (control food)
- Test food containing 31 times more omega-3 fat than the control food, and a 34-fold decrease in omega-6/omega-3 ratio, compared with the commercial control food
After the end of the six-month trial, the dogs fed the test food had significantly higher blood levels of omega-3s and significantly lower blood levels of a key pro-inflammatory omega-6 fat (arachidonic acid) at every blood test.
According to the reports provided by the owners of the dogs in the test and control groups, the canines fed omega-3-enriched food were significantly better able to rise from a resting position and play at six weeks, and showed an improved ability to walk at 12 and 24 weeks.
As the Kansas team wrote2, “…the test food raised blood concentrations of omega-3 fatty acids and appeared to improve the arthritic condition in pet dogs with osteoarthritis.”4
There are many anecdotal reports suggesting that omega-3 fish oil gives arthritic dogs relief… but it's even better to have this kind of scientific confirmation.
- Bauer JE. Responses of dogs to dietary omega-3 fatty acids. J Am Vet Med Assoc. 2007 Dec 1;231(11):1657-61. Review.
- Budsberg SC, Bartges JW. Nutrition and osteoarthritis in dogs: does it help? Vet Clin North Am Small Anim Pract. 2006 Nov;36(6):1307-23, vii. Review.
- Roush JK, Cross AR, Renberg WC, Dodd CE, Sixby KA, Fritsch DA, Allen TA, Jewell DE, Richardson DC, Leventhal PS, Hahn KA. Evaluation of the effects of dietary supplementation with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis. J Am Vet Med Assoc. 2010 Jan 1;236(1):67-73.
- Roush JK, Dodd CE, Fritsch DA, Allen TA, Jewell DE, Schoenherr WD, Richardson DC, Leventhal PS, Hahn KA. Multicenter veterinary practice assessment of the effects of omega-3 fatty acids on osteoarthritis in dogs. J Am Vet Med Assoc. 2010 Jan 1;236(1):59-66.
- Arthritis Foundation (AF). Arthritis in Dogs. 2010. Accessed at http://www.arthritis.org/arthritis-dogs.php