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Should I Use Fish Oil For Cats? - One cat looking at camera while other cats sit around watching the fisherman fish

Should I Use Fish Oil For Cats?

As a vet and a pet parent, I’ve seen the benefits of fish oil supplementation for cats firsthand. It’s become one of the most commonly recommended nutraceuticals by veterinarians — and for that reason, it’s also one of the most well-studied.

And while more research is still needed, there’s nothing fishy about these results!

Whether you use fish oil to support your feline friend’s overall skin and joint health or to help manage a specific medical condition, this omega-3-rich elixir is something that all pet parents should have in their (tackle) box.

What is fish oil?

While you’ve probably heard about the numerous health benefits of fish oil, you might not know that the nutrients supplied by fish oil aren’t just a “nice to have”. They’re critical for our furry family members!

But what exactly is fish oil? The terminology can be overwhelming, so let's break it down.

Fish oil is a supplement derived from fatty fish such as mackerel, trout, or salmon. It’s highly valued for its rich content of omega-3 fatty acids, specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).

These essential nutrients can’t be made by the body, so must be obtained through diet or supplementation. They play a role in a variety of bodily functions, and also offer valuable anti-inflammatory effects.

There are many types of fatty acids that can be classified in different ways based on their chemical makeup (for example: carbon chain length, saturated versus unsaturated, and location of double bonds). The most well-known are:

  • Omega-3 fatty acids: Found in fatty fish and certain plants like flaxseed, omega-3 fatty acids play a crucial role in brain development, heart health, and decreasing inflammation to promote healthy skin and joints.
  • Omega-6 fatty acids: Found primarily in vegetable oils, omega-6 fatty acids are also crucial for bodily functions such as normal reproduction, growth, and healthy skin. They’re considered pro-inflammatory, meaning they promote or cause inflammation. And hey, while that may sound like a bad thing, it’s actually an important part of the immune system, helping protect the body from infection and injury!

(However, an imbalance of omega-6 fatty acids can contribute to several chronic inflammatory conditions, so don’t go overboard with these.)

If you want to get nerdy about chemical composition, you can take a deeper dive into the makeup of these fatty acids.

Fish oil in a dropper that just got pulled from the bottle

But here’s what pet parents should know: both omega-3 and omega-6 fatty acids are critical for bodily functions and have different roles in managing inflammation in the body. And hitting the appropriate ratio between them is also important to provide the most benefit for our feline friends. A complete and balanced diet should contain an adequate amount of these essential nutrients.

The easiest way to add more beneficial omega-3 fatty acids into your cat’s diet? Fish oil.

Fish Oil for Cats Benefits

Fish oil owes its power to its high concentration of the omega-3 fatty acids EPA and DHA. The wide-ranging benefits of these fatty acids have been backed by multiple veterinary studies, and have been found to:

  • Decrease inflammation and support the immune system: The well-known anti-inflammatory effects of omega-3 fatty acids are critical for managing clinical signs of inflammation associated with several medical conditions in cats, ranging from allergies to kidney disease to cancer. They also strengthen the immune system to help fight off illness and infection.
  • Promote healthy skin and fur coat: These fatty acids help keep fur soft and shiny and minimize dryness, itchy skin, dandruff, and excessive shedding. They work by moisturizing the skin and decreasing signs of inflammation associated with common skin ailments like allergies and feline or canine acne.
  • Aid in joint health and mobility: Along with helping decrease inflammation in the joints, DHA and EPA also block enzymes that break down cartilage. This one-two punch allows cats with arthritis to maintain better mobility and comfort.
  • Support cognitive development and function: Studies have shown that omega-3s may be helpful in decreasing signs of cognitive dysfunction in middle-aged cats. (Side note: Fish oil supplementation also appears to improve trainability in puppies and support brain development in young animals! Start ‘em young, folks.)
  • Support vision and eye development: Omega-3s are important for eye development in kittens, and can help maintain eye health in adult cats.
  • Lower blood triglyceride levels: Supplementing with omega-3s has been shown to lower triglycerides in some animals.
(SIDE NOTE: Just like in humans, too much triglyceride or cholesterol circulating in the blood (a condition known as hyperlipidemia) isn’t healthy.
But here’s where things can get confusing. We also use the term triglyceride in a different way to describe a form of omega-3 fatty acid — and in that case, it’s a positive thing. So while the term "triglyceride" refers to a form of fat that we want to reduce in the body, it *also* refers to the preferred, most natural and absorbable form of fish oil supplement. Phew!)
  • Protects the heart: Benefits for the heart include lower blood pressure, lower triglyceride levels, prevention of blood clots, and prevention of abnormal heart rhythms like atrial fibrillation.
Cat looking up while licking lips waiting for fish oil

When should I use fish oil for cats?

Based on its many demonstrated benefits, you can see why fish oil can be beneficial for any cat. There are also certain times we specifically recommend fish oil to pet parents — like when cats are suffering from arthritis or mobility issues, skin concerns or allergies, or have a heart condition that would benefit from omega-3 supplementation.

Before adding fish oil to your cat’s diet, it’s important to discuss it with your vet. Omega-3 fatty acids are rarely used alone, so if your cat has one of the conditions listed below, they will likely need additional veterinary care and treatments:


Per the American Veterinary Medical Association, skin disorders, allergies, and ear infections are among the top seven health issues plaguing our feline friends.

While allergies in people often cause sniffles and sneezing, allergies in dogs and cats typically affect the skin, leading to pruritus (itchy skin), hair loss, inflammation, and secondary skin infections (oozing, crusting, scabs, sores, or pustules). Ouch!

Common culprits of cat allergies include fleas, the protein source in their diet, or something in the environment. Treatments include consistent year-round flea prevention, a hydrolyzed or novel protein diet for those with food allergies, medications (such as prednisolone, Atopica, or allergen-specific immunotherapy), and environmental modification to decrease the allergen load.

Any skin or ear infections must be treated with topical or oral antibiotics. And unfortunately, a cone of shame may be necessary to prevent further trauma from biting, chewing, and scratching itchy skin.

So where does fish oil come in? The essential fatty acids in fish oil help moisturize the skin while decreasing signs of inflammation (such as redness, itchy skin, and secondary skin infections). This leads to some visible improvement in a whopping 50% of cats!

These supplements may also reduce the need for other medications, similar to the results in these canine studies.


Many of us are likely familiar with osteoarthritis, either in ourselves or aging family members. So it shouldn’t be surprising that arthritis also affects cats — to the tune of 90% of cats over 12 years of age.

But cats are experts at hiding illness and discomfort, so the symptoms of arthritis observed by pet parents tend to be more subtle. That means cat arthritis is much more likely to go untreated.

Aside from the obvious limping and stiffness, cats with arthritis may show behavioral changes like:

  • Reluctance to jump onto furniture or use stairs
  • More time spent resting
  • Less time spent grooming and playing
  • Increased vocalization
  • Changes in posture
  • Changes in litter box use (or “going” outside the box)`

Checklists like this can be a useful tool for pet parents concerned about arthritis. Your vet can also diagnose arthritis based on a thorough history, nose-to-tail physical exam, and X-rays.

Dr. Elizabeth Colleran, an American Board of Veterinary Practitioners diplomat in feline medicine, recommends a multimodal treatment plan for her patients, including weight loss, medications (oral and injectible forms are available), environmental modification (think step stools or ramps to minimize jumping), and a special diet or omega-3 supplementation.

White cat with blue eyes peeking head outside of a box

How does fish oil work against symptoms of arthritis? It’s been shown to block enzymes responsible for the breakdown of cartilage, decrease inflammation, and improve mobility — helping to soothe sore joints and keep your cat moving.

Kidney disease

Chronic kidney disease (CKD) is a common and severe condition particularly prevalent in older cats (think 30-40% of cats over 10 years and 81% of cats over 15 years of age).

CKD involves the progressive loss of kidney function, leading to a decrease in the ability to filter waste products from the bloodstream. Typically diagnosed through blood and urine testing, clinical signs of CKD include increased thirst and urination, weight loss, poor coat quality, and decreased appetite. As the disease progresses, additional symptoms may include lethargy, vomiting, dehydration, and bad breath from ulcers in the mouth.

Unless a treatable underlying cause is identified, chronic kidney disease is a lifelong condition. While there’s no cure, CKD may be managed with dietary changes, fluid therapy, medications to treat the clinical signs, and management of related complications such as high blood pressure and anemia.

While more feline studies are needed, cats with CKD may live longer if fed a therapeutic diet high in omega-3s. Decreased protein loss through the urine has also been documented in dogs receiving this supplement.

Heart failure

Heart failure refers to a group of conditions affecting the heart’s ability to effectively pump blood, oxygen, and nutrients throughout the body. Clinical signs of heart failure in cats can be subtle, and may include decreased activity, difficulty breathing, loss of appetite, and weight loss.

More severe symptoms may include episodes of collapse, panting or respiratory distress, sudden hindlimb paralysis due to blood clot formation, or even sudden death.

Treatment will vary depending on the underlying cause and severity, but aims to control symptoms and improve quality of life. This may include medications to help the heart pump more effectively, diuretics to reduce fluid buildup, and more.

Omega-3s are beneficial for animals in heart failure for several reasons: they help decrease inflammation associated with underlying disease, support normal blood pressure, prevent muscle loss, and promote normal heart rhythms.


Omega-3 fatty acids are increasingly being researched for use in the treatment of cancers in both humans and animals alike. While anti-neoplastic effects (the ability to inhibit or prevent growth of cancerous cells) are still under investigation, the known anti-inflammatory properties of omega-3 supplementation make it a reasonable addition to cancer treatment plans in most cases. It can also help prevent muscle loss, known as cachexia, which is common in cancer patients.

Potential risks and side effects of fish oil for cats

Despite the popularity, minimal side effects, and wide safety margin associated with fish oil, no supplement or medication comes without risks. And in some cases, fish oil should be avoided or used with caution. Here are a few other things to consider:

  • Consult with your veterinarian: Before adding ANY supplement to your cat’s diet, it is important to check with your veterinarian. They’ll be able to make sure that the supplement is safe for your cat and provide guidance on appropriate dosing. The recommended dosage of fish oil may differ depending on your cat’s diet and what disease process you are trying to treat. Nutritional needs also vary between different life stages — for example, kittens, pregnant queens, etc.
  • Drug interactions: Fish oil may interact with certain medications or supplements, such as anticoagulants. Be sure to provide your vet with a list of all medications and supplements that your cat is taking.
  • Certain medical conditions: Cats with certain medical conditions (for example, those who are obese or have a history of pancreatitis) require a low-fat diet and should not take fish oil, which is high in fat. Fish oil is also not recommended for cats with blood clotting disorders or large non-healing wounds.
  • Side effects: What are the side effects of fish oil for cats? Especially at high doses, side effects of fish oil may include gastrointestinal upset (vomiting or diarrhea), fishy odor, oily skin, weight gain, delayed wound healing, pancreatitis, altered immune function, and abnormal bleeding or bruising. Starting with a low dose and giving fish oil with a meal should help decrease GI side effects. In most cases, side effects resolve after the supplement has been discontinued.
  • Overdose: Certain diets, such as those designed for skin or joint disease, may already contain high amounts of omega-3 fatty acids, and additional supplementation may exceed the recommended dosages. If you accidentally overdose your cat, contact your vet and watch for signs of gastrointestinal upset like vomiting and diarrhea. At high doses, vitamin A toxicity may occur.
  • Choosing the right kind of oil: Liver oils (for example, cod liver oil) should be avoided due to their high levels of vitamins A and D. And while flax and flaxseed oil do contain omega-3 fatty acids, they are in the form of alpha-linolenic acid (ALA), which should not be used in cats (and is not very effective for dogs either).
  • Manufacturing precautions: Be sure to choose a fish oil supplement from a reputable company that practices quality control to avoid issues like contamination from heavy metals, toxin exposure, or nutrient excess. Always use vet recommended fish oil for cats. 
Cat looking at a laptop reading about fish oil

What to do next

Whether you’re simply looking for a supplement to minimize the cat hair in your coffee, or trying to manage a significant medical condition, fish oil has potential benefits for any cat.

In summary, fish oil should be used for cats if:

  • There are no contraindications (health issues or medications that make the supplement unsafe)
  • Your furry friend’s diet does not contain sufficient amounts of EPA and DHA
  • Kitty has one of the medical conditions listed above, or another inflammatory disease process
  • It’s recommended by your veterinarian
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