This paper explored the efficacy of different levels of omega-3 fatty acids derived from fish oil, specifically EPA and DHA, in weight-bearing and lameness scores in dogs with osteoarthritis. Healthy dogs with radiographic changes of hip and/or stifle arthritis, clinical signs consistent with osteoarthritis, and consistent administration of medicine or supplements for at least 30 days prior to enrollment were included in the study. A total of 177 dogs completed the study. Dogs were fed 1 of 3 diets: foods A (a commercially available diet with fish oil), B, or C (foods B and C included additional marine oil concentrate). The amount of fish oil in foods B and C approximated roughly 2 and 3 times the amount of fatty acids in food A. All dogs were fed the experimental diets for a total of 90 days and were evaluated by their primary clinicians at regular intervals. Clinical evaluations assessed lameness, weight-bearing status, range of motion, reluctance to hold up contralateral limb, pain on palpation of affected joint, progression of arthritis, and overall arthritic condition. Scoring of patient osteoarthritis improved with increased fatty acid amounts in diets. In particular, there were significant improvements in lameness, weight bearing, overall arthritic condition, and arthritis progression in dogs fed food C. This is likely the result of a reduction in arachidonic acid as well as competitive inhibition of arachidonic acid conversion into eicosanoids by EPA and DHA. Adverse effects of the diets included diarrhea and vomiting, but these clinical signs did not reflect a dose dependent relationship with fatty-acid levels. Study supported by Hill’s Pet Nutrition, Inc

Commentary: It is known that fatty-acid supplementation is beneficial for joint health, and this study further supports the use of fatty acids at calculated higher dosages for optimum results. In addition, fatty acids are frequently prescribed to pets for a variety of clinical conditions. This study suggests that conventional store-bought diets may not contain fatty acids at therapeutic levels to reduce inflammation in arthritis patients. Certain pet owners may be unwilling or unable to switch to a therapeutic food. Accordingly, a direct source of fatty acids (capsules or liquid) may be preferred to store-bought products (which may not contain reliable or consistent therapeutic fatty acid percentages).—Heather Troyer, DVM, Diplomate ABVP (Canine & Feline Practice)

Dose-titration effects of fish oil in osteoarthritic dogs. Fritsch D, Allen TA, Dodd CE, et al. J VET INTERN MED 24:1020-1026, 2010.