This paper reviews studies during the past decade into the use of fatty acid supplements to treat various diseases in dogs. Fatty acids regulate normal physiology and mediate inflammation when metabolised into eicosanoids. The conclusion reached is that further investigation is needed into optimal levels of linoleic, gamma-linolenic and/or eicosapentaneoic acids in canine diets to enable normal homeostasis and treat inflammatory, degenerative and neoplastic diseases.