Fish Oil for Dogs and Cats: Dosage, Safety, and Health Benefits
- Cats and dogs have a limited ability to synthesize the omega-3 fatty acids EPA and DHA, and must rely on external sources
- Commercial pet foods typically contain higher amounts of omega-6 fatty acids and inadequate amounts of omega-3s EPA and DHA
- Supplementation with the omega-3 fatty acids EPA and DHA can provide a wide range of research-backed health benefits for cats and dogs
Pets are the best. And as their owners, it is our responsibility to make sure they feel and function their best. to give them the best in return.
Well, what if we told you that your pet is probably deficient in key nutrients affecting everything from their cellular health to their behavior and trainability. (Because if they eat commercial pet foods, they probably are.)
Many commercial pet foods—whether dry, canned, or raw—contain lower amounts of omega-3 fatty acids from fish oil and higher amounts of omega-6 fatty acids from vegetable oils.1 This is a problem, given that an unbalanced omega-6 to omega-3 ratio has been shown to negatively affect the health of animals’ skin, hearts, brains, and kidneys.2 Woof.
But don’t worry, we can help. In this article, we’ll talk about the importance of essential fatty acids for pets, and what dose of fish oil to give cats and dogs.
Essential Fatty Acids
Despite fat’s reputation for being “unhealthy,” it is quite important for cellular health. Fats provide energy, support the absorption of certain vitamins, and help modulate inflammation.2
A particularly important type of fats are polyunsaturated fatty acids (PUFAs). Often referred to as “healthy fats,” omega-3 and omega-6 fatty acids are required for the normal structure and function of cell membranes. However, because mammals lack the desaturase enzymes needed to make omega-3 and omega-6 fatty acids in the body, these essential PUFAs must be consumed through dietary sources.3
Sources and Metabolism
The three types of omega-3 fatty acids involved in human and animal physiology are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).
ALA is the parent fatty acid of the omega-3 family and gives rise to EPA and DHA through a complex series of metabolic reactions. It can be found in plant-based dietary sources including flaxseed, chia seeds, walnuts, and vegetable oils. EPA and DHA are found primarily in marine sources, such as fatty fish, fish oil, and phytoplankton.
Because cats and dogs are very limited in their ability to convert EPA and DHA from ALA, it is generally recommended that they obtain EPA and DHA directly from marine sources rather than ALA.3,4 For reasons we’ll explain in the coming section, it should also be noted that large doses of omega-3 ALA can actually lead to an essential fatty acid deficiency in cats, whereas supplementing with EPA and DHA does not pose the same concern.5
Sources and Metabolism
Omega-6 PUFAs, including linoleic acid (LA) and arachidonic acid (AA), are fatty acids found in vegetable oils, nuts, seeds, and animal meats. Like ALA, LA must be consumed through the diet in order to give rise to AA and its other long-chain PUFA derivatives. However, because cats show markedly little delta-6 desaturase activity (an enzyme needed to convert LA to AA), it is generally recommended that they obtain direct sources of AA.5
Differential Effects on Cellular Heath
When consumed in large amounts, omega-3 and omega-6 fatty acids have very different effects on overall health.6,7 Upon ingestion, both omega-3s and omega-6s are incorporated into membrane phospholipids where they play fundamental roles in regulating membrane properties and cellular signaling.7 However, whereas omega-3s help initiate cellular processes and signaling molecules that reduce cell stress and support a healthy inflammatory response, omega-6s can give rise to signaling molecules that promote an inflammatory response.7
What’s more, because omega-3s and omega-6s compete for the same enzymes needed to synthesize their PUFA derivatives, an increase in the omega-6 contents of a cell typically occurs at the expense of its omega-3s and vice versa.5,7 For this reason, feeding cats a diet high in ALA and low in LA can lead to an essential fat deficiency because ALA and LA will compete for the enzymes needed to synthesize AA. (In other words, either ALA will get the enzymes needed to synthesize EPA, or LA will get the enzymes needed to synthesize LA).
To help minimize the pro-inflammatory effects of omega-6s and maximize the health-promoting effects of omega-3s, it is generally advised that mammals consume a balanced ratio (around 6:1 or less) of omega-6s to omega-3s from EPA+DHA.5-7
Evidence-Based Benefits for Cats and Dogs
Still not convinced that omega-3s are vital for your pet’s health? A growing literature finds that supplementation with EPA and DHA can provide a wide range of beneficial effects for cats and dogs.6 EPA and DHA naturally occur and function together, but maintain their own distinct, yet mutually supportive role in promoting pet health.
EPA plays a significant role in:
- cellular and immune health 1,8
- heart health 9-12
- kidney health 13–16
- joint health 17-20
- skin and coat health 21-23
DHA plays a foundational role in:
- cellular and immune health 8,24,25
- brain development 26-29
- eye development 26,28
- trainability and behavioral health 29-32
Although comparatively fewer studies have looked at the effects of omega-3 supplementation in cats relative to dogs and humans, the evidence to date suggests EPA and DHA offer cats many of the same benefits as other mammals.1,2
Is My Pet Getting Enough Omega-3s?
If your cat or dog eats commercial pet food, check the nutrition label to see if fish oil is listed as an ingredient, or whether it has been enriched with EPA and DHA. Also keep in mind that even if the ingredients do list omega-3 sources (e.g., salmon, salmon meal, trout, etc.), many pet foods are manufactured at very high temperatures, which are detrimental to temperature-sensitive omega-3 fatty acids. This means that, even if their food does contain omega-3 sources, it will be difficult to know whether the amounts they are receiving are sufficient for foundational health.1,2
Compounding this issue further, because many commercial pet foods contain high amounts of omega-6s from vegetable oils, this will also affect the amount of omega-3 fatty acids that are ultimately available to your pet’s cells.5
How Much Omega-3 Fish Oil Does My Pet Need?
There isn’t a consensus on omega-3 dosage for animals; however, veterinarians and the National Research Council (a highly credible organization dedicated to the application of scientific research) generally adhere to the following weight-based recommendations for dogs and cats: 3
- 50-75 mg of EPA+DHA (combined) per kg of body weight
- 30-50 mg of EPA+DHA (combined) per kg of body weight
For reference, this amounts to a dose of 500-750 mg of EPA+DHA a day for a dog weighing 10 kg (~22 lbs.) and a dose of 150-250 mg of EPA+DHA per day for a cat weighing 5 kg (~11 lbs.). However, other variables factor into the amount of EPA and DHA your pet will need to meet its cellular health needs.
Size and Breed of Pet
Different animal breeds and sizes will require different amounts of PUFAs to maintain optimal cellular health.6
Stage of Life
Growing puppies and kittens often require greater amounts of omega-3s (particularly DHA) for proper retinal and brain development.3
Conditions affecting the health of the heart, kidneys, joints, and inflammatory response often require greater amounts of EPA+DHA.4,6
Amount of PUFAs Consumed in Diet
Different pet foods provide different amounts of PUFAs and will require different amounts of additional omega-3 supplementation.1
Considering all of these variables, we recommend talking to your pet’s veterinarian about how to best meet your pet’s omega-3 needs. This can be done most efficiently by providing EPA and DHA in a supplemental form, such as fish oil for cats and dogs.
Selecting a Quality Fish Oil Supplement
When choosing a fish oil supplement for your cat or dog, it is important to pick a product that’s:
- High in EPA and DHA—as opposed to ALA, which animals cannot convert into EPA and DHA efficiently.2,4
- Triglyceride form—as opposed to ethyl-ester or synthetic forms, which are less easily absorbed and utilized by the body than omega-3s in the natural triglyceride form.1,3
- Free of toxins and pollutants—pay special attention to whether the manufacturer takes measures to avoid common contaminants like mercury.2
- Manufactured and stored using methods that limit oxidation—the highly unsaturated nature of omega-3 fats makes them susceptible to rancidity, and special measures should be taken to reduce their exposure to heat, light, and other sources of oxidation.2
- Third-party tested for quality control—choose a manufacturer that voluntarily undergoes third-party testing to verify their ingredients, purity, and safety.
Potential Side Effects
Another important reason to talk to your pet’s veterinarian before starting with omega-3s (or any dietary supplement) is the potential for side effects. Although uncommon, instances of altered blood-clotting, gastrointestinal upset, increased oxidative stress, and altered wound-healing have been reported in cats and dogs.33 In order to better evaluate how your pet might handle starting a supplemental fish oil regimen, talk to their veterinarian.
If your cat or dog is lacking in important omega-3 fats, consult your veterinarian about whether and how much supplemental EPA and DHA they need for optimal health across life stages.
Desaturation: When a saturated compound gets converted into an unsaturated compound by the removal of two hydrogen molecules and the addition of a double bond.
Elongation: A metabolic process wherein a fatty acid’s carbon chain gets lengthened by an enzyme complex called elongase.
Fatty acid desaturase: Enzymes that introduce double bonds into fatty acid chains and help maintain the structure and function of cell membranes.
Phospholipids: A major component of all cell membranes; a type of lipid molecule made up of two fatty acids, a phosphate, and a glycerol molecule.