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fish oil for dogs

Fish Oil for Dogs – Benefits and Side Effects of Omega-3 Supplements

Fish oil can help dogs with a variety of medical issues. We look at the benefits and side effects of treating dogs with fish oil supplements.

There is no shortage of nutritional supplements available for dogs, with marketers promising all sorts of potential benefits, whether accurately or not. But fish oil is one supplement that is widely recommended and approved of by veterinarians. Let’s look at the various benefits, risks, and side effects of fish oil supplements for dogs.

What Is Fish Oil? 

Nutrition groups and diet specialists have been touting the benefits of fish oil for many years. For the unaware, fish oil is a source of omega-3 fatty acids that cannot be created by our—or our dogs’—bodies. As the name suggests, fish oil is found in certain types of fish including sardines, anchovies, and salmon. 

Two of the omega-3 fatty acids in fish oil, eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids, can help reduce inflammation. In comparison, many grains and processed foods (including many dog foods) are high in omega-6 fatty acids. These can provide some health benefits but may cause harm when not balanced with an adequate source of omega-3 foods or supplements.

What Benefits Do Dogs Get from Fish Oil Supplements?

A primary benefit dogs receive from fish oil supplements is a reduction in inflammation as a result of their omega-3 fatty acids. This can often positively impact certain health problems a dog may be experiencing. There are also some minor risks, which we will look at later.

These are the most common health conditions in dogs that fish oil supplements are used to treat:

Treatment of Arthritis and Joint Pain in Dogs

Arthritis is a swelling and tenderness in joints, so anti-inflammatories such as omega-3 fatty acids are a logical treatment. Prescription diets for dogs with arthritis often include substantial amounts of fish oil. Anecdotally, we’ve seen significant improvements in our aging, arthritic dogs’ mobility when taking fish oil supplements.

Prevention and Treatment of Heart Issues in Dogs

Just as humans often supplement with fish oil to both prevent and help manage cardiovascular issues, vets often recommend fish oil supplements for dogs as well. In addition to its anti-inflammatory properties, fish oil also can help protect against abnormal heart rhythms (arrhythmia or atrial fibrillation).

Dogs with heart issues often lose excessive weight — not just fat but also essential lean body mass, and fish oil supplements are known to help keep this weight on the dog in these situations.

The omega-3s in fish oil also have an anti-clotting effect that can reduce the likelihood of certain heart problems. However, this anti-clotting effect would be harmful for a hemophiliac dog; thus, always check with your vet to make sure the supplement is appropriate based on your dog’s particular health history.

Treatment of Inflammatory Skin Conditions in Dogs

Skin conditions are some of the most common dog ailments, and fish oil supplements can help them significantly. Whether the result of allergies or other diseases affecting the skin, dog skin conditions often respond well to fish oil, making them less irritating and uncomfortable. 

Fish oil can reduce the body’s production of inflammation stimulators, called cytokines, which in turn can reduce the degree of itchiness. Studies have shown that dogs are less likely to scratch and chew at itchy, flaky skin conditions while taking fish oil supplements, especially when these conditions are in their early stages of development.

Fish oil also has the potential to improve the quality, shine, and softness of a dog’s fur, but care should be taken to avoid overdosing so that the fur does not become too oily. 

Treatment of Toenail Conditions in Dogs

Dog dermatologists often recommend fish oil to promote nail growth and health. Dog toenails often grow much faster and stronger when fish oil supplements are given, and this can help speed up recovery from broken or damaged nails. 

Fish oil can also aid in the treatment of other nail issues such as fungal growth and infections when taken along with other medications.

Dogs who have brittle nails or weak nails either naturally or as a result of other ailments such as autoimmune diseases can benefit fish oil supplements.

Treatment of Canine Cognitive Dysfunction

Often referred to as dog dementia, canine cognitive dysfunction is a condition found in older dogs where their mental faculties are diminished. Studies have found that one omega-3 fatty acid in particular, DHA, can help slow down the progression of this condition, and sometimes even improve the cognitive function.

Canine cognitive dysfunction syndrome has a host of behavioral symptoms including confusion, disorientation, barking at nothing in the night, and other altered behaviors. Managing the condition will take more than simply giving fish oil supplements to the dog, but it can play a role in the overall treatment of the syndrome.

Treatment of Kidney Disease in Dogs

Fish oil supplements have been shown to provide benefits for various kidney diseases and disorders. In failing kidneys, the supplements may lower elevated blood pressure. The anti-inflammatory properties of fish oil can also benefit kidneys that are compromised.

Fish oil may also help with glomerular disease, a disorder of the kidneys that causes undesired protein loss in urine. Studies have shown it to help slow down the progression of kidney damage from this disorder.

Is Fish Oil Safe for Dogs?

Yes, fish oil is safe for many dogs. As noted above, some vets may prescribe or suggest fish oil supplements in addition to medications to help dogs with arthritis, certain allergies, and several other medical issues. If you think your dog could benefit from fish oil supplements, you will first want to check with your vet to ensure that your dog does not have any medical conditions or medications with which the fish oil could interfere. 

Fish oil is sold as a supplement, but dogs can also reap many of the same omega-3 benefits by eating the fish commonly used in fish oil supplements, including anchovies, sardines, and salmon. 

If you plan to add omega-3-heavy fish to your dog’s diet, be aware that wild-caught fish are a much better source of omega-3 fatty acids than farm-raised fish. It may be easier to simply add a fish oil tablet, pill, or liquid supplement to your dog’s food rather than more dramatically modifying their meals. 

Can I Give My Dog Fish Oil Meant for Humans?

Although it is safe for many humans and dogs to take fish oil supplements, supplements intended for humans are not always safe for canine consumption. This is the case primarily because fish oil supplements made for humans may contain sweeteners or other additional ingredients that are not safe for dogs to eat. 

Additionally, it may be more difficult to determine the correct dosing amount for your dog from pills intended for human consumption. Fish oil supplements for dogs are created with canine dosing guidelines in mind and make accidental overdosing less likely.

If a fish oil supplement intended for humans is made solely of fish oil, it may be safe for your dog to consume. It would be a good idea to consult with your vet first, though, to ensure that the supplement in question is truly safe for your dog as well as to find out exact dosing guidelines. 

Potential Side Effects of Fish Oil for Dogs

Side effects from fish oil primarily are related to overdosing, although even smaller quantities of some types of fish oil may cause dogs to have fishy breath. Another side effect not related to overdosing is the fact that fish oil works as a blood thinner. This can be positive—especially in decreasing likelihood of blood clots—but could also be a health risk for dogs with bleeding problems like hemophilia. 

Another risk is related to the anti-inflammatory properties of fish oil. While a decreased inflammatory response can help address certain health problems, others may be exacerbated: for instance, wounds may take longer to heal because of a suppressed inflammatory immune response.

You also may have come across a widely shared article “I Almost Killed My Dog With Fish Oil,” about a dog who developed a vitamin E deficiency from excessive supplementation with fish oil pills. To combat this risk, some fish oil supplements are compounded with vitamin E. Although fairly rare, vitamin E deficiency can cause a number of worrisome symptoms and further underscores the need for vet oversight when adding supplements to a pet’s diet. 

Some other side effects dogs may experience from fish oil supplement overdosing include oily fur, sleepiness, diarrhea, or vomiting. 

Side effects related to stomach upset (e.g., diarrhea and vomiting) may also occur as a response to a modification to the dog’s diet. For this reason, it is important to introduce the supplement slowly and with the direction of a vet.

Pills, Capsules, or Liquid Fish Oil for Dogs

Fish oil supplements are available in capsule, chewable pill, and liquid forms. The gel cap form is usually used for fish oil supplements intended for humans, although some canine-friendly gel cap pills are also available. The best type for your dog will depend on factors such as whether or not they take pills easily and whether or not they like the smell of fish oil. 

Fish Oil Pills for Dogs

If giving your dog pills is a struggle, you might consider a chewable fish oil supplement. One such fish oil supplement tablet for dogs is Amazing Nutritionals’ Omega 3 Chews. These tablets are bacon and liver flavored, which may be a better option for dogs who do not like fish (or for individuals sensitive to the smell of fish). 

It should be noted that this fish oil supplement also includes sunflower and evening primrose oils, both of which are safe for most dogs to consume. These ingredients are sources of omega-6 and omega-9 fatty acids in addition to the fish oil’s omega-3s; if you are looking for a pill containing only fish oil, you will want to look at alternative options. 

Capsule/Gel Cap Fish Oil for Dogs

One gel cap fish oil supplement intended for human consumption but safe under certain circumstances for dogs is Nature’s Bounty Fish Oil Softgels. A few things to note if you are considering this option are that it may be better to poke holes in the gel cap so that your dog does not eat the gel cap and that dosing may be more difficult with this option because it was made with human dosing in mind.

If you choose a capsule pill that is not made with dogs in mind, make sure to verify the safety of the pill and dosing requirements with your vet. 

Liquid Fish Oil for Dogs

A liquid fish oil supplement may be a good idea for dogs who do not take pills easily; one liquid fish oil supplement option is Vital Pet Life’s Premium Essential Wild Alaskan Salmon Oil. This liquid fish oil includes both a pump and flip cap along with dosing instructions for each type of cap and is added directly to your dog’s food. 

Another benefit of this particular option is that it does not include ingredients outside of the fish used for the oil. That being said, check with your vet first before adding it to your dog’s diet.

Fish Oil Dosage for Dogs

Although you should rely on your vet for exact dosing recommendations, fish oil dosing suggestions for dogs not taking the supplement for specific health conditions vary depending on the supplement’s form (i.e., capsule, pill, or liquid). Dosing can be further complicated by factors such as the decision to give your dog a fish oil supplement intended for humans; in that scenario, you would need to follow your vet’s direction so that your dog does not receive an overdose of fish oil. 

Canine-aimed fish oil supplements should include dosing guidelines on their packaging, but it is a good idea to first check with your vet. If your dog has certain health issues that need a higher dose of fish oil to address, your vet can tell you what amount is safe to give them. It is important to follow your vet’s guidelines because appropriate dosing will depend on your dog’s size and their health history. 

Unless your vet directs you otherwise based on a specific health concern, though, it may be wise to dose on the lower side at least initially to ensure that your dog does not experience fish oil overdose side effects.


Adding fish oil to dogs’ diets increases the amount of omega-3 in their diets and can provide some health benefits. Before making any changes, though, be sure to consult your vet. It is important to take care that the dosing is correct when adding the fish oil supplement to your dog’s diet so that your dog can avoid the side effects and receive the benefits. 

Chelsea Dickan

Chelsea Dickan

Chelsea Dickan is a long-time advocate for animals, especially those that bark or meow. When she isn't writing, she enjoys reading and watching scary movies in which the dog doesn't die.