Essential Fatty Acid (EFAs) Supplementation and Absorption


Ideally, dogs and cats that are fed a well balanced natural raw diet should not require supplementation with EFAs. However, some patients probably benefit from having extra EFAs. Especially animals with joint pain or skin and heart problems.

EFAs are fats that must be supplied in the diet because the body cannot produce them. They are required for normal growth and functioning of the cells, muscles, nerves, and organs and the production of prostaglandins. EFAs are divided into two groups: Omega 3 and Omega 6. The numbers in the name indicate the first carbon double bond position on the fatty acid chain. All essential fatty acids are polyunsaturated, the 3 and the 6 mean that the first double bond is either 3 or 6 carbons in from the end.

The ratio of these EFAs in the diet is important but recommendations range between 8:1 and 2:1 for Omega 6 : Omega 3. Supplementing with higher levels of Omega 3 appear to be more beneficial so 2:1 is likely to help skin conditions more than 8:1.

Grains and cereals are high in Omega 6 EFAs. These form the bulk of most commercial preparations marketed for feeding dogs. Consequently, animals that are fed this highly processed product are likely to be deficient in Omega 3s. Animals that are fed meat from factory farms can also be deficient in Omega 3s due to the high levels of grains that are fed.


What are the best sources of EFAs to use?

Fatty acids are considered either "active" or "inactive". It appears that some dogs produce enzymes which can help activate EFAs that are classified as being inactive.

Cod liver oil and fish oils (salmon, herring etc.) supply activated Omega 3 EFA's (EPA and DHA).

Flaxseed and hemp oils are inactive (ALA).

If a dog produces the enzymes required to activate the inactive EFA's, it does not matter whether you supplement active or inactive forms. If a dog does not produce the required enzymes, or not enough of them, supplementation of active EFA's that do not require enzymes to be utilised is required.

If you supply inactive sources (eg Flaxseed oil) and notice apparent benefits, there is no need to supply activated sources (eg Fish oil). If you start EFA supplementation with inactive sources and do not notice associated changes within a time frame of several weeks, you might want to consider giving the active sources a try instead.

Omega 3 fatty acids oxidise rapidly and increase antioxidant requirements in the body. So the best policy would be to supplement with vitamin E as well.


Vegetable oils (canola, corn, soy), sunflower and safflower oil are common sources of inactive Omega 6 EFAs.


For more information, see


Feeding an egg (especially the yolk) once or twice a week is also a good source of EFAs.


What is the correct dose?

This question has not yet been determined, and depends how much the animal is already obtaining in its diet.

You can use the following as a guideline. It may be prudent to start with a lower dose and increase accordingly.

Cod Liver Oil: 1/2 to 2 teaspoons depending on the size of the animal. Fermented Cod Liver Oil is a better option since digestibility is improved.

Fish Oil: 50mg/Kg Eicosapentaenoic acid (EPA).

Note that most Fish Oil preparations are labelled with the total amount of EFAs in each capsule or ml of liquid. You need to read the label further to find out how much EPA (one of the Omega 3 EFAs) the product contains so that you can calculate how much to give.

Fish oils can contain concentrated levels of heavy metals including Mercury.

It may be better to add raw fish to the diet instead of Cod Liver Oil or Fish oil. This is more natural than giving a fish oil supplement, and will avoid excess heavy metals if fish that are at the low end of the food chain are used (eg sardines, anchovies and herring).

Further information on Fish Oils is on

Flaxseed Oil : 1 teaspoon to 2 tablespoons depending on the size of the dog.

Remember to store Flaxseed oil in the refrigerator.

There may be little or no benefit in feeding Flaxseed oil to cats since it is unclear whether cats are unable to convert the inactive ALA into the active EPA and DHA forms of Omega 3.




Best to feed fish (oily sustainable varieties that are low in the food chain eg sardines, anchovies, herring)

Feeding an egg once or twice a week is also a good idea

Alternatively, supplement with Omega 3 EFAs

Cod Liver Oil and Fish Oil may be better than Flaxseed oil

(Other common vegetable oils are poor sources of Omega 3 EFAs)

Calculate the amount required; this may be more than initially expected


Dr Douglas Wilson


Page last edited: Apr 19th 2016

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