There are two main reasons why we include fat in the diet of dogs and cats: to provide energy (calories) and for essential fatty acids (EFAs- aka omegas).
Most adult pets live relatively sedentary lives and so do not require foods with high concentrations of fat. Essential fatty acids, however, are needed by ALL dogs whether they are involved in intensive activities or not. It is important to note that some level of dietary fat is required in the diet to act as a carrier for the fat-soluble vitamins current AAFCO recommendations are 5% for adult maintenance and 8% for growth & reproduction (1). That being said, dogs and cats can both do very well on diets with wide fat content ranges as long as the other nutrients are accounted for.
Essential Fatty Acids (EFAs)
There are two families of essential fatty acids that dogs and cats require: omega-6s and omega-3s. Omega-9 fatty acids can be synthesized in the body and are therefore not considered essential.
Both omega-6 and omega-3 fatty acids are “important in the diet, but dog foods (like human foods) tend to contain an overabundance of omega-6 fatty acids simply because of the types of ingredients that are produced in our modern agricultural system”. So while omega-6s are important, they are not usually the main focus of supplementation.
Why are Omega-3s Important?
Omega-3 fatty acids have many vital functions in the body that all play a role in the animals overall health and vitality.
➳For example, omega-3s support brain development, skin and coat health, immune and cardiovascular function, and reproduction (both pregnancy and lactation). Furthermore, increasing omega-3 fatty acids in the diet may also have therapeutic benefits such as “managing certain types of chronic inflammatory disorders in dogs such as joint pain due to arthritis and allergic skin problems.”
➳They are also essential for young animals as “recent research indicates that DHA is important for the development of a healthy nervous system and vision in fetuses and newborn[s]…and may promote learning in young puppies”
A Closer Look
For dogs and cats, there are “good” sources of omega-3s and “bad” sources of omega 3s and it all comes down to bioavailability. There are SO many pet foods on the market that claim to be high in omega-3s that are not using bioavailable sources.
Let’s unpack that a bit…
There are three key omega-3s that people focus on: ALA, EPA, & DHA. Alpha linolenic acid (ALA) comes from plant-based sources like flax and hemp seeds. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can either come from ALA being converted in the body or from a marine-based food in animal’s diet. HOWEVER, (and this is a BIG HOWEVER), dogs and cats -unlike other mammals- do not do this conversion efficiently. While most mammals (including people) can convert some ALA into EPA & DHA, this process is thought to be pretty inefficient in dogs and cats (1) .Which is why I prefer to use marine-based sources of omega-3 fatty acids because no conversion is required in the body.
Once the EFAs are in the body, ALA is (very poorly) converted to EPA & DHA and is thought to be important for the maintenance of a healthy transepidermal water barrier. EPA is further broken down to hormone-like agents called eicosanoids. Which “regulate fundamental physiological processes such as cell division and growth, blood clotting, muscle activity, secretion of digestive juices and hormones, and movement of substances like calcium into and out of cells” (2). DHA is used for brain development and function. “Synapses are rich in DHA, which suggests that this fatty acid is involved in signal transmission along neurons” (2).
Pet Foods “Containing” Omega-3s
Many pet foods claim to have a high omega-3 content rendering supplementing unnecessary (according to them). However, a large majority of these foods are using flax or hemp as the primary omega-3 source. Reading the the label to look for ingredients like hemp or flax is a good idea but even then, the only way to really know how much omega-3 is coming from a plant-based source vs how much may be coming from an added fish oil is to have a lab test done for the specific fatty acids- so how much ALA, how EPA & how much DHA. On top of that, (not to be a Nancy naysayer) but even for those premium brands that are using primarily fish-based sources of their omega-3 content, and listing that proudly on their label, you then have to think about the stability of those products.
Unfortunately, omega-3s are extremely sensitive to heat and oxygen exposure and will go rancid very quickly. Pet food formulator Steve Brown remind us in his book Unlocking the Canine Ancestral Diet that “although the original DHA content of the food [may be] listed on the bag, it is not necessarily the amount of DHA that is in the food when you feed it to your dog” (3).
When it comes to giving omega-3s to dogs and cats, careful sourcing is essential. As we’ve already discussed, you’ll want to look for a marine-based source as they will be richest in EPA & DHA.
Plant sources of omega-3s like hemp or flax are less desirable for sourcing DHA & EPA but can still be useful for other nutritional purposes. To keep this post from being too long, I’m just going to focus on a few key sources of omega-3s), there are other options out there, I’d recommend doing some research if you are interested in learning about other sources.
➵ Whole Fish (carefully sourced)
Whole fish contain not just EPA and DHA, but vitamin D, selenium, protein, cofactors, and a more complete fatty acid profile than fish oil. They are also less predisposed to rancidity as their cell walls are intact.
➵ Green Lipped Mussel
Whole green lipped mussel contains 680 mg of omega-3 from EPA and DHA per 100g serving (4). You can also find freeze-dried powders on the market which can be more convenient although you’ll want to inquire as to their process to ensure the essential fatty acids (EFAs) are as preserved as possible (I typically ask for lab testing to show EFA levels of the product post-processing).
➵ Fish Oil
This is my least favorite source of EFAs but it is probably the one most people are most familiar with, and it is certainly an extremely popular option in the pet food market.
So as we know, EPA & DHA are super prone to rancidity and so the processing and storage of fish oils is an extremely delicate process (5). If you’re going to use a fish oil supplement, source it VERY carefully! Use one containing small fish like sardine, anchovy, or herring, and are stored in glass containers. Also I recommend looking for ones that only use triple phase molecular distillation and not ethanol distillation as molecular distillation will remove pollutants and leave the fish oil more stable and less likely to degrade.
A quick way to tell which process your fish oil brand uses is to pour some of your oil into a styrofoam cup, if the oil eats through the cup in 30 minutes or less you may have an oil that was distilled with ethanol.
Another thing to consider when adding fats like fish oil is that you can very easily throw off the nutrient balance of your diet. “Minerals are needed to help metabolize fats; adding fat to a food without adding minerals can impair fat absorption, throw off the fat/mineral balance, and can lead to mineral deficiencies” (3).
Giving too much fish oil without adding sufficient antioxidants (e.g. vitamin E) can have negative long term effects (6). Although there are some fish oils on the market that contain vitamin E they often only contain enough to make their product more shelf stable, and not enough for your pet’s body to use them as an antioxidant. To clarify what approach your fish oil brand takes, I recommend contacting them specifically. If you do choose to add fish oils to your pet’s diet, you’ll want to ensure you are also giving a natural source of Vitamin E as well.
1. Canine and Feline Nutrition: a Resource for Companion Animal Professionals by Linda P Case et al.
3. Brown, Steve. Unlocking the Canine Ancestral Diet. p 15 & 48
6. Brown, Steve. Beth, Taylor. See Spot Live Longer. PG 118.