Analysis of selected nutrients and contaminants in fish oil supplements for dogs

Fish oil supplements for dogs are used therapeutically for various clinical conditions. However, products may be variable in quality, potency, and stability. The objective of this study was to analyze eleven canine fish oil supplements from two time points (2010 and 2021) for the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), polychlorinated biphenyl (PCB) arochlors, minerals, and vitamins A and D, and to compare their compositions to label claims. Molybdenum, cadmium, mercury, lead, and PCBs were not detected in any samples. Other minerals were detected in some products, and concentrations were well below general maximum tolerable levels or applicable regulatory maximums for dog foods. EPA and DHA concentrations varied widely among products and between timepoints. Overall, there were six instances of products not meeting label claims within 5 % for EPA, DHA, or both. Across both timepoints, five minimum content claims were made for vitamin A, and three for vitamin D. In 2010, the analyzed concentrations were below the claims for one product each for vitamins A and D, while for 2021 all products met their respective claims. Overall, products were assessed to have low risk for vitamins A and D or mineral toxicoses when used as recommended. At higher (therapeutic) doses, contributions to the overall intake for nutrients of concern should be considered, including selenium and fat soluble vitamins. In addition, there is room for improvement for manufacturers to ensure accurate label guarantees.