International Omega-3 Learning and Education Consortium for Health and Medicine

Omega-6 fatty acids and omega-3 fatty acids are two families of essential fatty acids that are crucial to the growth, development and health of our dogs and cats. These essential fatty acids must be in the petfoods we give to our dogs and cats. Since dogs and cats cannot produce these fatty acids in the body, they must be supplied in the diet, and thus they are called "essential fatty acids" ¹. The essential fatty acid requirements for the dog and cat are published in the "Nutrient Requirements of Dogs and Cats" published in 2006 by the National Research Council, The National Academies Press ¹.

Omega-6 and omega-3 fatty acids serve different functions in the body. Two important omega-6 fatty acids are linoleic acid (LA or 18:2n-6) and arachidonic acid (AA or 20:4n-6). For more information on the chemistry of omega-3 and omega-6 fatty acids refer to Omega-3 Fatty Acid Structures on the consortium website. In dogs, LA from the diet can be converted to AA in the body; therefore, AA is not considered essential for dogs (Figure 1). In PUFA formation the amounts of both omega-3 and omega-6 essential 18 carbon fatty acids are in competition for the rate regulating enzyme of PUFA formation (the enzyme Δ6 desaturase). This enzyme dictates the family of 20 and 22 carbon PUFA formed in the dog (Figure 1). In dogs, LA from the diet can be converted to AA in the body; hence, AA is not considered essential for dogs (Figure 1). However, cats cannot produce enough AA from LA in their body, and so AA is essential for cats [2]. In both pets, the primary omega-6 essential fatty acid LA is the most important fatty acid in maintaining healthy skin and coat as well as other vital functions in the body. Without enough LA, dogs and cats will experience dull, dry coat; hair loss; greasy skin and increased susceptibility to skin inflammation. AA is used by the body of the dog and cat for synthesis of regulatory molecules called eicosanoids that are fundamental in maintaining overall body function (especially during growth), and in the following systems: reproductive, immune, intestinal, endocrine, respiratory, heart and vascular, and nervous. The eicosanoids are produced by enzymes called cyclooxygenase (COX) and lipoxygenase (LOX) as shown in Figure 1. Another substrate for the synthesis of COX and LOX products is 20:3n-6 (Figure 1).

There are four important omega-3 fatty acids, alpha-linolenic acid (ALA), stearidonic acid (SDA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (Figure 1). Dogs can convert ALA to EPA and DHA, but the conversion is not efficient and it is not likely that dogs can make adequate amount of EPA and DHA endogenously from ALA. Similar to AA, cats lack the ability to convert ALA to EPA and DHA ². Therefore, EPA and DHA are considered essential for cats. In the body, EPA shares the same metabolic fate as AA; that is, it can be used to form regulatory molecules, albeit much weaker ones, in physiological potency. DHA is the most abundant structural component in the brain and throughout the nervous system, and especially in the retina. It is also a major fatty acid in sperm.

Traditionally, petfoods for dogs and cats are packed with excessive amounts of omega-6 fatty acids, primarily LA. This is good when the amount is appropriate, but not when their amount is too much. Along with the industrialization of our agriculture system, too much omega-6 fatty acids have been introduced into petfoods, as well as in our own diet. For humans, a typical Western diet contains 10 times or more omega-6 than omega-3 fatty acids ³. A similar situation applies to petfoods since we share a lot of agricultural products in our diets. However, current knowledge indicates that a balanced ratio of omega-6 to omega-3 fatty acids of 5:1 would be the most beneficial to the health of pets and humans. When too much AA is present in the body, it promotes inflammation and exacerbates disease conditions, such as skin disease, arthritis, and renal problems.

Many nutritionists believe that there is an ideal balance between the omega-6 and omega-3 fatty acids for the pet. However, since every pet is unique (in a specific age group, at a specific life stage, and with varying health conditions) the "ideal balance" could be unique to that pet and its ideal omega-6 and omega-3 balance could be different from that of other pets. We recommend a generalized ratio of omega-6 to omega-3 of 5:1 for a healthy pet. The petfood company, Iams, is a pioneer in omega-3 research in dogs and cats and their results indicate that ratios from 5:1 to 10:1 of omega-6 to omega-3 fatty acids is good for pets. If you believe your pet is having any health problems, you should consult a veterinarian for advice.

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