Fatty acids fall into three groups: saturated (mostly from animal fats), monounsaturated (olive oil, poultry fat), and polyunsaturated (the omega-3s and omega-6s). Within polyunsaturated, omega-3 (EPA, DHA, ALA) and omega-6 (linoleic, arachidonic) play opposing roles — omega-6 generally pro-inflammatory, omega-3 generally anti-inflammatory. The omega-6 to omega-3 ratio matters as much as absolute amounts; the modern pet food problem is excess omega-6 from corn/soy/poultry-fat-heavy diets. Cats cannot convert ALA to EPA/DHA; dogs do so inefficiently.