I Almost Killed My Dog With Fish Oil

almost killed dog fish
Photo by Howard Young on Flickr

We all have been told of how incredibly important fish oil is in our dog’s diet, because it’s a rich source of omega-3 fatty acids. 

Yes, fish oil is great for dogs and has many potential health benefits. 

Since most dogs get a shed-load of omega-6 fats from their processed food, a healthy amount of omega-3 is essential to counteract the inflammatory effects of excess omega-6. 

Fish oil is a highly recommended supplement for dogs, and has many positive health effects.

But, before you go overboard with giving your pet fish oil, you should also know that there are many side effects to excessive consumption of it; especially vitamin E deficiency. 

Read on to find out all you need to know before giving your dog fish oil supplements… 

What you will learn from this article:

  1. Is fish oil toxic to dogs?
  2. How does fish oil affect dogs?
  3. How do I tell if my dog needs fish oil?
  4. Can a dog overdose on fish oil?
  5. Can fish oil become rancid and poisonous?
  6. What is the best type of fish oil for dogs? 
  7. Best and safest alternatives to fish oil
  8. Can fish oil kill a dog?
  9. Closing Thoughts

Is fish oil toxic to dogs?

Fish oil is not toxic to dogs. In fact, it’s one of the most common supplements given to both dogs and cats, and it’s generally safe for pets. 

Numerous studies have confirmed that the omega-3 fatty acids present in fish oil are very beneficial to dogs. 

And some of these benefits include anti-inflammatory effects, better skin and coat quality, among many others.

How does fish oil affect dogs?

Fish oil is a great source of omega-3 fatty acids, such as, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 

EPA and DHA are anti-inflammatory agents and are excellent for boosting the nutritional content of your dog’s diet. 

The effects of fish oil on a dog will largely depend on the overall health and diet of the dog.

For instance, a dog with an inflammatory skin disease and dull coat will experience a dramatic change in appearance within a few weeks of fish oil supplementation. 

Dogs who suffer arthritis, diabetes, kidney disease, heart disease, or cancer, have a lot to gain from fish oil. 

Older dogs with cognitive dysfunction to help improve cognitive function. 

Fish oil is also great for puppies as it aids in proper eye and brain development, and boosts the canine immune system. 

Since it’s rich in anti-inflammatory agents, fish makes a great ingredient in your dog’s food, especially if your pet is on a dry diet. 

Finally, here’s a quick rundown of the benefits of fish oil for your dog;

  • Fights inflammation and boosts immune system
  • Improves the health and quality of dog skin and coat, also helps with allergies
  • Reduces the risk of cancer, heart disease, kidney disease, etc
  • Promotes eye health and brain function
  • Improves joint and bone health, also helps to relieve arthritis
  • Helps to fight inflammatory bowel disease and improves gut health.

Despite these positive effects of fish oil, it can also be very dangerous for your canine. Fish oil is great. 

But, giving your pet too much of it can decrease the level of vitamin E in your pet’s body and cause a deficiency of the vitamin with very severe symptoms including; lameness, severe pain, premature aging, depletion of muscle tone, edema, weight loss, etc.

How do I tell if my dog needs fish oil?

So you’ve heard a lot of great things about Omega-3 fats and how fish oil is the best way to help your pet get some. 

And now, you can’t help but wonder if your pet needs some of this goodness, and how you can tell if you should give them some. Well, if you feed your dog mostly kibbles and a dry diet, then chances are they do need fish oil supplements. 

Processed dog food is mostly made from grains, refined oil and meat from grain-fed animals, which are all rich in Omega-6 fatty acids, with very little or no Omega-3 fatty acids. 

Therefore, you need some supplementation to create a healthy balance of Omega-3 and Omega-6 fatty acids in your dog’s diet. And fish oil happens to be a great option. 

On the other hand, if you feed your dog a raw diet of meat from grass-fed animals, or you occasionally include a healthy dose of salmon, tuna, sardines or any fish at all to your dog diet, then they may not need the extra Omega-3 from fish oil, because they are already getting it from their food.

Another way to tell if your pooch needs more omega-3 is if they happen to have dry or dull coats with flaky skin, arthritis or joint stiffness, skin allergies and brittle/poor nail quality. 

These are some of the obvious signs that your canine may need fish oil supplementation. 

Also, if you have a dog with special needs, such as an illness, then fish oil supplements can help. 

When giving your canine companion fish oil supplements, there are a few things to keep in mind: 

  1. First, make sure you use only fish oil from reputable sources of fish oil to avoid heavy metal toxicity
  2. Be extra careful with giving fish oil to your dog if they have blood-clotting disorder or are taking anticoagulant medications. Fish oil supplements tend to increase anti-clotting effects
  3. If your dog is pregnant, consult with your vet before giving her fish oil pills
  4. Also, avoid fish oil supplements if you have a pet with oil sensitivity or has a history of pancreatitis. 
  5. And finally, strictly follow the recommended dosage.

Can a dog overdose on fish oil?

As a matter of fact, dogs can overdose on fish oil, and giving your dog an extremely high dose of fish oil will cause some side effects. 

An overdose of fish oil can cause some of these symptoms;

  • Diarrhea and vomiting
  • Oily coat or flaky skin
  • Reduced blood clotting
  • Delayed wound healing
  • Internal bleeding
  • Lameness
  • Weight gain
  • Altered immune function, etc.

According to the National Research Council, between 20 and 55 mg of combined EPA and DHA is a safe dose for dogs. 

This is just for dogs without any serious health conditions or special needs. 

Canine fish oil supplements also come with recommended dosage and administration guidelines to help pet parents use them safely.

However, before adding fish oil to your pet’s food, it’s important that you consult your vet for dosage recommendations, because dogs vary in size, weight, age and breed. 

Can fish oil become rancid and poisonous?

The Omega-3 fatty acids (EPA and DHA) in fish oil are polyunsaturated fats which are very unstable. 

Therefore, fish oil is unstable and quick to oxidize. In other words, fish oil becomes rancid when exposed to oxygen, which is one of the major disadvantages of fish oil supplements. 

However, when properly stored in dark containers and away from light, it can be preserved for much longer. 

When in use, fish oil should be properly covered and refrigerated to prevent oxidation.

Rancid fish oil smells and tastes bad, and it should not be given to your pet. 

Rancid fish oil is toxic and consumption can result in organ damage. 

If your fish oil has a fishy taste or smell, then it’s bad or rancid and should be thrown away.

What is the best type of fish oil for dogs?

When shopping for fish oil supplements, be very picky and choose only the highest quality products. 

Highest quality doesn’t equate to most expensive, as there are many budget-friendly fish oil supplements with excellent quality. 

First, you have to remember that fish oil supplements which come from unknown sources may contain toxins and heavy metals like lead and mercury from ocean contaminants absorbed by fishes. 

And certain fish species tend to have more contaminants and heavy metal deposits than others.

Another thing to look out for is the type of fish oil, and here are 3 types you will find;

  1. Natural triglyceride oil: this is the most natural form and highest quality fish oil, but not necessarily the purest. It is also the easiest for the body to absorb.
  2. Ethyl ester oil: this is a semi-natural form of fish oil. It is concentrated and distilled to remove impurities.
  3. Synthetic triglyceride oil: this is the synthetic form of fish oil and least absorbable. 

Here are two recommendations for budget-friendly natural fish oil for your dog:

  • Nordic Naturals Omega 3 Pets Supplement: made in the USA from wild anchovies and sardines from the cleanest waters. It’s in the true triglyceride form for optimal absorption and has many positive reviews on Amazon.
  • Sea Pet Omega Plus Fish Oil with Natural vitamin E: this is concentrated human-grade omega-3 with 200 UIs natural vitamin E per teaspoon, enough for your pet’s body  to utilize as an antioxidant. It’s also made from sardines and anchovies.

Best and safest alternatives to fish oil

The best and safest alternative to fish oil, is the actual source of fish oil; fish. 

Food in its whole form is far better than isolated, processed and mass-produced as supplements in pills. 

The good news is that dogs don’t need large amounts of omega-3 and including oily fish in your dog’s diets, at least once or twice every week, is better than any fish oil you can give them. 

The best oily fishes for dogs include; salmon, tuna, mackerel, anchovy, whitefish, herring, cod, whiting, carp, and trout

These fishes are considered to be very nutritious and rich in the much-needed omega-3 fats.

Can fish oil kill a dog?

To finish off this article, I want to answer a blunt but important question about just how dangerous fish oil can be to dogs.

A simple answer to this question is that fish oil can kill your dog although it is incredibly unlikely.

Even as I write this, I’m having to pinch myself about what I’m writing.

It just seems so absurd that a product which is held up as a miracle food or at least a miracle supplement can cause so much damage.

So let me explain.

Fish oil isn’t dangerous in and of itself to your dog for the many reasons that have been discussed in this article.

The trouble comes with how a dog’s body absorbs the oil and what it uses to do this.

Most of us that are adding fish oil to a dog’s diet are doing it via tablets or pills.

In order to absorb this oil a dog’s body will use vitamin E and it will use so much of it that it hasn’t enough left over for other vital functions.

You see, vitamin E plays an important role in your dog’s body helping to support crucial functions that range from maintaining muscles to maintaining a healthy coat. 

Now feeding your dog a few cod liver oil capsules now and again won’t harm them at all.

The trouble comes when fish oil is added to a dog’s diet over weeks, months or years

And this is when their body might become drained of vitamin E.

The safest way to add fish oil to your dog’s diet is to not to add it on a regular or continual basis. 

Closing Thoughts

Fish oil is an excellent source of omega-3 fatty acids, which have tremendous benefits for your dog’s health. 

Adding fish oil supplements to your dog’s diet is a good way to ensure your pet gets some omega-3, however, make sure you consult your vet and stick to the recommended dosage. 

This is because an excess of fish oil in your dog’s diet can also cause vitamin E deficiency, among other negative effects. 

Therefore, make sure that you feed your dog high-quality food that is rich in vitamin E, or include vitamin E supplements in their diet, to prevent this effect. 

James Grayston

My name is James and I love dogs. have owned four Golden Retrievers in the past 15 years. Currently I own two "Goldies"- a five year old and a seven month old. The photo shows me with our youngest when she was about 7 weeks old!