Dried blood spot-based omega-3 fatty acid status assessment in dogs: The Omega-3 Index concept and its dermatological perspective - Short communication.

Long-chain omega-3 fatty acids (ω-3 FAs), particularly eicosapentaenoic acid (EPA, C20:5 ω-3) and docosahexaenoic acid (DHA, C22:6 ω-3), are widely used in canine medicine as nutritional adjuncts in chronic inflammatory and degenerative diseases. Blood-based biomarkers, especially erythrocyte fatty acid composition, provide an integrated measure of long-term ω-3 FA exposure and are less susceptible to short-term dietary fluctuations than plasma indices. Within this framework, the Omega-3 Index (O3I) - the sum of 2 prominent long-chain ω3 fatty acids (EPA and DHA) in erythrocyte membranes, expressed as a percentage of total erythrocyte FAs - offers a standardised, biologically anchored metric of ω-3 FA status with potential relevance for clinical evaluation and monitoring. Studies in healthy dogs demonstrate low baseline O3I levels, while dietary supplementation with marine-derived ω-3 FAs reliably increases both circulating plasma concentrations and erythrocyte-based indices of ω-3 FA status. In dogs with chronic diseases such as osteoarthritis, cardiac diseases, and selected gastrointestinal disorders, reduced ω-3 FA status is observed and supplementation results in measurable biochemical changes (lower content of triglyceride and total cholesterol, better antioxidant status, reduced production of prostaglandin E2 and interleukin-6). In contrast, comparable erythrocyte-based data are very limited in canine dermatology. Although species-specific reference ranges and outcome-based targets are not yet established, assessment of ω-3 FA status offers a promising tool for monitoring FA supply, guiding supplementation and supporting individualised clinical nutritional management in canine practice.