Fatty Acids - A Panacea or Pandora's Box?

The importance of essential fatty acids (EFAs)and the role they play in the homeostasis of metabolic pathways has been studied in a variety of species since 1929. However, the number of double-blind cross-over studies in dogs and cats has been relatively few. Nevertheless, dietary supplementation with any one of a variety of products available to the practitioner has gained widespread usage. Many pet food manufacturers have also started adding fatty acids to their diets for a number of years, in part to satisfy perceived nutritional and medical benefits, but also for marketing reasons. In spite of this widespread usage, many practitioners remain confused about the role EFAs play in therapeutics.

In the dog, cis-linoleic acid is the only essential fatty acid while, in the cat, both cis-linoleic and arachidonic acid are essential. Other fatty acids, such as eicosapentaenoic are very important, but not essential.

In recent years there has been an increase in claims about role that fatty acids may play in a wide variety of clinical applications, including dermatitis, arthritis, renal disease, immunological disorders, cancer, cardiovascular disease and wound healing.

Dietary supplementation has been most widely utilized in the treatment of keratinization disorders and inflammatory skin disease. Many studies have been done in this area and fatty acid supplementation has become an important form of complementary therapy in the treatment of many skin diseases.

Omega-3 fatty acids are involved in the inhibition of the growth and the spread of cancer in mice. Studies have also shown that the spread of cancer has been enhanced by the n-6 fatty acids, linoleic and gamma-linolenic acid. Omega-3 fatty acids are also effective in reducing cachexia associated with some forms of cancer as well as the negative effects of radiation therapy. From this early work, the future impact in cancer treatment holds promise.

There is consistent evidence from double-blind, placebo-controlled, clinical studies in humans with rheumatoid arthritis that dietary supplementation with n-3 fatty acids can alleviate clinical signs. In one study done on dogs looking at the potential benefits of n-3 fatty acids on atopy, many of the dogs with concurrent hip dysplasia showed an improvement in musculoskeletal signs. There exists the potential for complementary fatty acid therapy and drug therapy in the treatment of some forms of arthritis. In other areas, initial work has shown promise with the effect of n-3 fatty acids on lowering blood pressure and its negative effects in kidney disease.

While EFAs show promise, clinically, studies on long term negative effects from fatty acid supplementation are generally lacking. The major safety issues of long-term dietary intake of n-3 fatty acids include increased tissue breakdown bleeding disorders and negative effect of the immune system. There is evidence that the n-3 fatty acids can negatively impact wound healing. There is also a growing frustration amongst clinicians over the discrepancy between theoretical and achieved clinical response. Although there are likely many reasons for this disparity, one explanation may be the lack of understanding as to what dose ranges are ideal and what ratios of n-6 to n-3 are most appropriate. Clearly, this has not been established. Further investigation is required. In the meantime, dietary supplementation with omega fatty acids will undoubtedly continue to be an effective complement in the treatment of many clinical diseases in small animal medicine.