Hyperthyroidism is the most common endocrine disease in domestic cats. This study examined whether dietary iodine restriction can reduce thyroid hormone concentrations in hyperthyroid cats. We performed a 12-week randomized, blinded, prospective study in which hyperthyroid pet cats housed with their owners were fed a control food (n=15) or a prototype restricted iodine food (n=18). Elemental analysis confirmed that iodine levels were approximately 10-fold lower in the restricted iodine food than in the control food. In the restricted iodine group, serum total thyroxine (TT4), free thyroxine, triiodothyronine, creatinine, and alanine transaminase significantly decreased, while blood urea nitrogen, aspartate transaminase, and alkaline phosphatase did not significantly change. In contrast, in cats fed the control food, alanine transaminase and aspartate transaminase significantly increased, but none of the other measures changed. In the according-to-protocol. cohort, at the end of the study, all 12 cats in the restricted iodine group had decreased TT4 concentrations, whereas in the control group, TT4 concentrations had decreased in four cats, increased in four, and not changed in two (p=0.0028). At the end of the study, 6 of 12 cats in the restricted iodine group and 0 of 10 in the control group were euthyroid (p=0.015). None of the cats in either group became hypothyroid, and body weights and urine specific gravity did not significantly change. These results show that over 12 weeks, feeding a restricted iodine food reduces serum thyroid hormone concentrations in hyperthyroid cats without negatively affecting other measures of health. Feeding a restricted iodine food warrants further study as a treatment option for feline hyperthyroidism.

OBJECTIVE To evaluate the effects of a food supplemented with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis. DESIGN Randomized, double-blinded, controlled clinical trial. ANIMALS 38 client-owned dogs with osteoarthritis examined at 2 university veterinary clinics. PROCEDURES Dogs were randomly assigned to receive a typical commercial food (n = 16) or a test food (22) containing 3.5% fish oil omega-3 fatty acids. On day 0 (before the trial began) and days 45 and 90 after the trial began, investigators conducted orthopedic evaluations and force-plate analyses of the most severely affected limb of each dog, and owners completed questionnaires to characterize their dogs' arthritis signs. RESULTS The change in mean peak vertical force between days 90 and 0 was significant for the test-food group (5.6%) but not for the control-food group (0.4%). Improvement in peak vertical force values was evident in 82% of the dogs in the test-food group, compared with 38% 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 on day 90, compared with measurements obtained on day 0. CONCLUSIONS AND CLINICAL RELEVANCE 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.

OBJECTIVETo determine the effects of feeding a diet supplemented with fish oil omega-3 fatty acids on carprofen dosage in dogs with osteoarthritis.DESIGNRandomized, controlled, multisite clinical trial.ANIMALS131 client-owned dogs with stable chronic osteoarthritis examined at 33 privately owned veterinary hospitals in the United States.PROCEDURESIn all dogs, the dosage of carprofen was standardized over a 3-week period to approximately 4.4 mg/kg/d (2 mg/lb/d), PO. Dogs were then randomly assigned to receive a food supplemented with fish oil omega-3 fatty acids or a control food with low omega-3 fatty acid content, and 3, 6, 9, and 12 weeks later, investigators made decisions regarding increasing or decreasing the carprofen dosage on the basis of investigator assessments of 5 clinical signs and owner assessments of 15 signs.RESULTSLinear regression analysis indicated that over the 12-week study period, carprofen dosage decreased significantly faster among dogs fed the supplemented diet than among dogs fed the control diet. The distribution of changes in carprofen dosage for dogs in the control group was significantly different from the distribution of changes in carprofen dosage for dogs in the test group.CONCLUSIONS AND CLINICAL RELEVANCEResults suggested that in dogs with chronic osteoarthritis receiving carprofen because of signs of pain, feeding a diet supplemented with fish oil omega-3 fatty acids may allow for a reduction in carprofen dosage.

OBJECTIVE:To assess the effect of food containing high concentrations of fish oil omega-3 fatty acids and a low omega-6-omega-3 fatty acid ratio on clinical signs of osteoarthritis in dogs.DESIGN:Randomized, double-blinded, controlled clinical trial.ANIMALS:127 client-owned dogs with osteoarthritis in 1 or more joints from 18 privately owned veterinary clinics.PROCEDURES:Dogs were randomly assigned to be fed for 6 months with a typical commercial food or a test food containing a 31-fold increase in total omega-3 fatty acid content and a 34-fold decrease in omega-6-omega-3 ratio, compared with the control food. Dog owners completed a questionnaire about their dog's arthritic condition, and investigators performed a physical examination and collected samples for a CBC and serum biochemical analyses (including measurement of fatty acids concentration) at the onset of the study and at 6, 12, and 24 weeks afterward.RESULTS:Dogs fed the test food had a significantly higher serum concentration of total omega-3 fatty acids and a significantly lower serum concentration of arachidonic acid at 6, 12, and 24 weeks. According to owners, dogs fed the test food had a significantly improved ability to rise from a resting position and play at 6 weeks and improved ability to walk at 12 and 24 weeks, compared with control dogs.CONCLUSIONS AND CLINICAL RELEVANCE:Ingestion of the test food raised blood concentrations of omega-3 fatty acids and appeared to improve the arthritic condition in pet dogs with osteoarthritis.