Dangers of Too Much Fish Oil for Dogs

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Happy Dogs Fish Oil

You have probably already heard of the many benefits of fish oil supplementation in dogs. The best fish oil supplements can be used as adjunct treatment in many inflammatory conditions, such as cancer, kidney disease, joint disease, dementia, and hair and skin problems.

Just like humans, the diets of dogs in the United States are low in anti-inflammatory omega 3 fatty acids DHA and EPA, and high in pro-inflammatory omega 6 fatty acids. Fish oil is rich source of anti-inflammatory omega 3 fatty acids, and supplementing your dog’s diet with fish oil can balance the fatty acid scales, but is there a danger with giving too much?

As with all things, the key is moderation. Turns out that when it comes to fish oil, there is such a thing as too much of a good thing.

Over-supplementation with fish oil can have adverse effects on your dog’s health, and fish oil is not recommended for dogs with certain conditions, or dogs undergoing surgery.

Here are the other things you need to be aware of with fish oil:

1. Delayed Wound Healing

Delayed Wound Healing Dogs Fish Oil

EPA and DHA are the two main omega 3 fatty acids found in fish oil. Both EPA and DHA are considered to be anti-inflammatory, and the anti-inflammatory properties interfere with wound healing. Inflammation isn’t always a bad thing! When the body is wounded, it sends inflammatory signals to send white blood cells to the edges of the wound to prevent infection and start healing. EPA and DHA interfere with inflammation, and can slow wound healing. If your dog is healing from a wound, discontinue fish oil administration until your dog is fully healed.

2. Bleeding Disorders

Both EPA and DHA can affect platelet function. Platelets are tiny white cells in the blood that are crucial to blood clotting. Blood clotting is how your body prevents hemorrhaging from wounds or trauma.

EPA and DHA, at high doses, interfere with and reduce clotting ability in platelets. Dogs that are fed high doses of fish oil are at higher risk of bleeding excessively. This most affects dogs that may bleed due to trauma or surgery, and if your dog is on high doses of fish oil, be sure to inform your veterinarian, especially if your dog is scheduled to have surgery. Your veterinarian may have you discontinue the fish oil before, during, and after the surgery until your dog has fully healed.

3. Negative Gastrointestinal Effects

The dosage of fish oil recommended for dogs with joint disease, kidney disease, or other inflammatory conditions is much higher than the standard dose, and may cause gastrointestinal disorders. If omega 3 fatty acids aren’t digested properly, the excessive fat can cause secretory diarrhea. Vomiting has also been reported. If your dog is required to take high levels of omega-3 fatty acids for a health condition, it is generally recommended to start at a lower dosage and slowly transition your dog to the higher dose to prevent any stomach or intestinal upset.

Pancreatitis is also something to be concerned about in dogs that are being fed high levels of fish oil. The risk at this point is theoretical, because there are no known reports of dogs developing pancreatitis in response to fish oil administration, however, in dogs that are at risk of developing pancreatitis, supplementing with fish oil should be done under the supervision of a veterinarian.

4. Trans Fats

We all know that trans fats are bad for you – right? Fish oil is comprised of cis fats, which are opposite of trans fats and considered ‘good’. However, omega 3 fatty acids are highly unstable and subject to oxidation, which can convert them into bad fats!

Fish oil turns rancid in the presence of light, heat, and oxygen. In order to make sure the fish oil you are giving is protected, fresh, and beneficial to your dog’s health, buy from reputable companies, and store fish oil in the fridge freezer, and make sure the container is opaque to protect the supplement from light.


Lenox CE, Bauer JE. Potential adverse effects of omega-3 Fatty acids in dogs and cats. J Vet Intern Med. 2013 Mar-Apr;27(2):217-26. doi: 10.1111/jvim.12033. Epub 2013 Jan 16.

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