Comparison of Fish, Krill and Flaxseed as Omega-3 Sources to Increase the Omega-3 Index in Dogs

SIMPLE SUMMARY: For pets, as for humans, dietary inclusion of long-chain omega-3 fatty acids is recommended for disease prevention and improved health. However, many diets for dogs do not contain sufficient amounts of these fatty acids and fall short of achieving high blood omega-3 levels. This is reflected in the diagnostic health tool called Omega-3 Index (O3I). In this study, O3I levels were measured at baseline in 45 dogs fed a commercial premium diet and compared to O3I levels reached when the dogs were fed with diets containing different omega-3 sources at low inclusion levels, i.e., fish meal/oil, flaxseed cake and krill meal. After four weeks of treatment, the data showed that the highest O3I increase was observed in the 3% krill meal group, accompanied by the lowest arachidonic acid to eicosapentaenoic acid ratio as a measure for immunomodulatory effects. Hence, by using the O3I, this study provides an option for dog owners to measure the impact their pet food has on their dogs’ health and if needed, how to adjust it with the right omega-3 supplement. ABSTRACT: (1) Background: it is only the longer chain omega-3 polyunsaturated fatty acids (n-3 PUFAs), eicosapentaenoic acid (20:5n-3, EPA), and docosahexaenoic acid (22:6n-3, DHA) and not the shorter chain α-linolenic acid (ALA, 18:3n-3) that have been linked to health benefits. (2) Methods: 45 dogs divided into three groups were first given premium dry food for 38 days (baseline). The O3I was then used as a diagnostic tool to provide a measure of the sum of EPA + DHA in red blood cell membranes given as a percentage of all fatty acids. The dogs were subsequently fed with either krill meal (krill), fishmeal/oil (fish) or flaxseed cake (flax) included in raw food providing daily 416 mg EPA + DHA (971 mg ALA), 513 mg EPA + DHA (1027 mg ALA) and 1465 mg ALA (122 mg EPA + DHA), respectively. (3) Results: the average baseline O3I level of all dogs was low (1.36%), warranting n-3 supplementation. After four weeks, O3I levels were significantly increased in the krill (from 1.36 ± 0.44 to 2.36 ± 0.39%) and fish (from 1.35 ± 0.22 to 1.9 ± 0.35%) groups (p < 0.001). No significant modification of the O3I was detected in the flax animals. (4) Conclusions: only marine n-3 PUFAs resulted in a significantly increased O3I, with dietary krill meal providing the highest increase.