There's one aspect of nutrition that many people – including vets – can find particularly daunting: fats and oils. There have been mixed messages over the years about good fats/ bad fats, essential oils/ unnecessary oils, long chain/short chain, saturated/unsaturated. This is one area where Wikivet can help – for veterinary professionals as well as members of the public. The Wikivet section about fatty acids provides a clear, comprehensive summary.
Technical stuff about fatty acids that vets need to know (optional for pet owners)
The most important facts are worth summarising in ten key points:
1) The terms “fats” and “oils” tend to be replaced by “fatty acids” by nutritionists, as it is the fatty acids in fats and oils that give them their most significant properties.
2) Fatty acids (FA) are carboxylic acids with long hydrocarbon chains, which can be saturated or unsaturated.
3) Saturated fatty acids have single bonds, and tend to have a high melting point making them more likely to be solid at room temperature (e.g. butter or fat on meat)
4) Unsaturated fatty acids have at least one double bond, and tend to have a low melting point so tend to be liquid at room temperature (e.g. olive oil)
5) Mammals are able to synthesize certain saturated fatty acids from other dietary components (such as glucose and proteins) so they do not need to have these in the diet.
6) Dogs and cats, like other mammals, have an essential dietary requirement for certain unsaturated fatty acids since they cannot be manufactured in their bodies: omega-3 and omega-6: these are known as "essential fatty acids".
7) (A technical point, but an important one for biochemistry nerds): Omega-3 FAs are a family of unsaturated fatty acids that have a double bond in the third carbon-carbon bond: the most important are Alpha-linolenic acid (ALA), Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)
8) Omega-6 FAs are a family of unsaturated fatty acids that have a double bond in the sixth carbon-carbon bond: e.g. linoleic acid (LA) is an essential ingredient in animal diets. Others in the group include Gamma linolenic acid (GLA), Dihomo-gamma-linolenic acid (DGLA) and Arachidonic acid (AA) (which is essential for cats, but not for dogs).
9) Omega-3 and omega-6 fatty acids are in competition for the same metabolic enzymes in the body and the ratio of omega-6 to omega-3 fatty acids, as well as the total amount of each type, is important.
10) (The key take home point!) These essential unsaturated fatty acids are important for growth (including the development of the brain and eyes), for skin and coat function (including influencing allergic skin disease)
What does this all mean in practice for pet owners?
First, choose a good quality diet that is adequately supplemented with the right proportions of omega-3 and omega-6 unsaturated fatty acids.The optimal ratio of omega-6 to omega-3 fatty acids is thought to be between 10:1 to 5:1. Most pet foods contain far more omega-6 fatty acids than omega-3. Omega-3 fatty acids are sometimes added to commercial pet foods to lower the ratio of omega-6 to omega-3 fatty acids.
Second, if your pet suffers from skin disease, in particular, or poor skin/coat quality, talk to your vet about dietary supplements to enhance their omega-3 and omega-6 intake, aiming to get both the absolute quantity and the ratio correct.
Third, remember that it takes around six weeks for a dietary supplement of fatty acids to make a visible difference to the quality of a pet's coat.
Fourth and finally, if you have a good head for understanding chemistry and nutrition, go ahead and read the Wikivet article, and better again, look up the references at the end. This is pure nutritional science, as good as you can get, and it's what pet food companies use to formulate the products on the shop shelves. It may be hard to follow sometimes, but the best way to optimal nutrition is to fully understand the science behind what you feed your pet.