Fatty acids are essential components of cell membranes and are an integral component of the intercellular barrier in the stratum corneum. Essential fatty acids cannot be synthesized and therefore must be supplied in the diet. The essential fatty acids most important for homeostasis of the skin in dogs and cats are linoleic acid and linolenic acid. The anti-inflammatory properties of fatty acids are thought to be due to competitive inhibition of arachidonic acid metabolism, leading to a reduction in inflammatory leukotriene and prostaglandin synthesis and activity, and to the formation of metabolic byproducts of normal fatty acid metabolism that have direct anti-inflammatory properties.
Essential fatty acids are indicated for pruritic inflammatory diseases (eg, allergies, feline eosinophilic granuloma), crusting diseases (eg, discoid lupus erythematosus), and onychodystrophy. Many commercial products are available and may be used at the manufacturers’ recommended dose. Lack of response to one product does not preclude response to another, and increasing the dose to several times the label recommendation can help in some cases. Approximately 20% of dogs and 50% of cats with allergic pruritus will show some improvement. There are few adverse effects; however, pancreatitis has rarely been reported. Large doses may also cause weight gain or diarrhea.