For many years, pet owners have given fatty acids to their dogs and cats to change a dull, dry coat into a more glossy one. More recently veterinarians have found that fatty acids play important roles in other areas of skin and coat health such as allergies, the control of inflammation, and the function of other body organs in dogs and cats.
What are fatty acids?
Fatty acids are specific types of polyunsaturated fats.
The two main classes of fatty acids we will be discussing are the omega-3's and the omega-6's. These classifications are based on molecular characteristics. (For you biochemistry buffs out there, check out the text box at the end of this article.) You may also have heard about omega-9 fatty acids. Omega-9's actually decrease the concentrations of omega-3 and omega-6 fatty acids in the blood and skin.
Which fatty acids do pets need?
Animals can produce some of the fatty acids they need, but not all of them. Those fatty acids which they can not produce themselves, but must be obtained through their diet, are called 'essential' fatty acids. Interestingly, what is 'essential' for one species of animal is not necessarily essential for another. For example, the fatty acid, arachidonic acid is essential for cats but not for dogs.
In some disease conditions, certain enzymes which convert one fatty acid to another may be deficient, or the animal may not be able to adequately absorb fatty acids from the intestine. In animals with these conditions, some of the 'nonessential' fatty acids actually become 'essential,' that is, required in the diet, and in higher amounts. Deficiencies of fatty acids may also occur with the use of fat-restricted diets in overweight dogs.
Fatty acids in foods are subject to degradation. Overcooking can destroy fatty acids. Improper storage or a suboptimal amount of antioxidants in dry food may result in rancidity and a subsequent deficiency in fatty acids.
Omega-3 fatty acids:
Alpha-linolenic acid (ALA)
Eicosapentaenoic acid (EPA)
Docosahexaenoic acid (DHA)
ALA can be converted into EPA, however, this conversion does not occur in the skin. EPA is the workhorse of the omega-3 fatty acids and is incorporated into the cell membrane.
Omega-6 fatty acids
Linoleic acid (LA)
Gamma linolenic acid (GLA)
Dihomo-gamma-linolenic acid (DGLA)
Arachidonic acid (AA)
LA can be converted into GLA, but not in the skin. However, DGLA can be made from GLA in the skin.
LA is important because it optimizes water permeability in the skin. AA, on the other hand, in increased amounts, is the troublemaker among the fatty acids.
Ratios of fatty acids
Research is being performed to determine the optimal ratio of omega-6 to omega-3 fatty acids that should be consumed. Previously, it was thought that the ratio should be approximately 15:1. Current recommendations are for ratios of 10:1 to 5:1.
Most pet foods contain far more omega-6 fatty acids than omega-3's. Some pet food companies have added omega-3 fatty acids to their foods to lower the ratio of omega-6 to omega-3 fatty acids. It is important to realize that although the ratios may be a guideline, the actual concentration of EPA in the omega-3's is what is most important.
Sources of fatty acids
Fat may contain fatty acids, but in extremely varying quantities. For example, beef fat will have a very low percentage of fatty acids, whereas, sunflower oil and fish oil will have much larger percentages.
Essential fatty acids are found in different quantities in many plants and cold water fish. Marine oils are good sources of EPA and DPA. The other fatty acids are found in higher quantities in certain plants and grains. Sunflower oil and safflower oil are especially high in LA.
For animals allergic to fish, the seeds of the Salvia hispanica plant provide a rich source of omega-3 fatty acids. The seeds of the plant contain their own antioxidants. A Salvia hispanica equine product called Tri-Omega has recently been approved by the FDA for use in horses.
As mentioned previously, most pet foods contain far more omega-6 than omega-3 fatty acids. It has been found that cattle and poultry fed increased omega-3 fatty acids will produce meat and eggs higher in omega-3 fatty acids. In the future, the use of these products in pet food may help to optimize the omega-6 to omega-3 ratio in the diet.
How fatty acids function in inflammation
EPA, DHA, and DGLA decrease the harmful effects of AA.
Both AA and EPA can be incorporated into cell membranes. When a cell is damaged, AA is released from the cell membrane and is metabolized by enzymes into substances which increase inflammation and pruritus (itching). EPA is also released when a cell is damaged. It competes with AA for the same metabolic enzymes. EPA results in the production of less inflammatory substances. DHA also results in the production of less inflammatory substances. So DHA and EPA decrease the harmful effects of AA.
DGLA also competes with AA for enzymes. In addition, DGLA causes the release of prostaglandin E1 (PGE), a substance which inhibits the release of AA from the cell membrane.