Best Omega 3 for Cats: 8 Smart Checks Before You Buy

The best omega 3 for cats is a marine oil, such as fish or krill oil, that lists mg of EPA and DHA on the label. It also comes from a maker with clear quality control. Pick a form your cat accepts, skip cod liver oil unless your vet approves, and let your vet set the dose.

This guide is a buying checklist, not a brand ranking. If you want the basics first, start with our omega-3 for cats guide, which covers what these fats do.

What makes the best omega 3 for cats

Here we focus on one question. How do you tell a good product from a weak one before you pay? So we walk through source, label, quality, form and safety, step by step.

There is no single winner for every cat. Instead, the best omega 3 for cats is the one that passes a short list of checks and suits your own cat.

Think of it like reading a food label. First, you look at what is inside. Then you ask who made it and how. The same habit helps you spot the best omega 3 for cats. Finally, you ask your vet if it fits your cat.

Eight checks for the best omega 3 for cats

1. Source: marine oil with EPA and DHA, not only plant oil.
2. Label: mg of EPA and DHA per serving.
3. Quality: a maker that can explain its QC testing.
4. Seal: know what NASC does and does not prove.
5. Form: liquid, capsule, chew or paste your cat will take.
6. Cod liver oil: a vet-only choice because of vitamin A.
7. Safety: side effects, drug clashes and health history.
8. Diet and dose: check the food, then let your vet set the amount.

The rest of this guide takes each check in turn. Also, the table further down puts the common forms side by side.

Marine EPA and DHA vs plant ALA

This is the first and biggest check. Cats are not like people when it comes to plant omega-3s.

According to a board-certified vet nutritionist writing in Today's Veterinary Practice, cats turn almost no plant ALA into EPA. The reason is low activity of an enzyme called delta-6 desaturase.

So the best omega 3 for cats supplies EPA and DHA directly. That same review says fish oil is the most efficient way to do it, not flaxseed.

The NASC says much the same thing. Cats have trouble converting plant ALA into EPA and DHA. Also, EPA and DHA usually show up together in marine sources, such as fish oil or krill oil.

Shopping tips for the best omega 3 for cats

• Look for fish oil, krill oil or another marine oil near the top of the ingredient list.
• Treat flaxseed, hemp or chia oil as weak picks if they are the only omega-3 source. They are rarely the best omega 3 for cats.
• Watch for products that say "omega-3" on the front but list only plant oils on the back.

For a deeper look at these two fats, see our guide to EPA and DHA for cats.

How to read the label on the best omega 3 for cats

Here is a fact that surprises many owners. Not every "omega-3" product contains EPA or DHA at all.

So the Today's Veterinary Practice review advises you to check the label. If the amounts are missing, ask the maker for the EPA, DHA and ALA content.

Count mg of EPA and DHA, not total oil

A 2020 dosing review in the same journal makes a key point. Vets set fish oil doses by mg of EPA and DHA, not by total oil.

That matters because two oils with the same volume can hold very different amounts. So the best omega 3 for cats tells you the mg, not just the oil size. Also, the review says makers should give you enough detail to work out the mg of EPA and DHA.

• Good sign: "EPA X mg, DHA Y mg per serving" printed clearly.
• Weaker sign: only "fish oil 1,000 mg" with no breakdown.
• Red flag: no amounts at all, and the maker will not share them.

A clear label is a mark of the best omega 3 for cats. So bring it to your vet, who can turn those mg numbers into a plan for your cat.

Quality checks and the NASC seal

Pet supplements do not go through the same review as drugs. The FDA says animal supplements do not fall under the human supplement law, DSHEA. Instead, the FDA treats them as food or drugs, based on their ingredients and intended use.

Also, the FDA notes that animal food does not need pre-market review. AAHA NEWStat puts it plainly: there is remarkably little oversight of supplement makers.

So the maker matters a lot when you look for the best omega 3 for cats. The Today's Veterinary Practice review suggests you buy from a reputable company with good quality control. Then ask about QC testing or third-party checks.

What the NASC seal means

The National Animal Supplement Council runs the NASC Quality Seal. To display it, a member company must pass an on-site quality audit.

• A written quality control manual and procedures.
• A system to report adverse events and complaints.
• Labels that carry FDA-CVM and NASC warning or caution statements.

PetMD's vet author recommends looking for the seal. AAHA also notes it means the product came from a facility that passed an independent audit.

What the NASC seal does not mean

However, the seal reflects a company and facility audit. It is not a lab test of each product or each batch.

So the seal helps you narrow down the best omega 3 for cats, but it is not the whole answer. You still need to read the label and ask about testing. The NASC also lists the members that passed, so you can check a brand yourself.

Useful yardstick: the WSAVA Global Nutrition Committee suggests judging pet food makers on expertise, staff and quality control. The same questions work well for supplement makers too.

Forms compared for the best omega 3 for cats

PetMD says fish oil for cats most often comes as a liquid. You can also find gel capsules, pills, chews and pastes.

The best omega 3 for cats is also one your cat will take every day. So form matters as much as source.

VCA notes that fish oil comes as capsules or liquid. With a liquid, measure each dose with care so your cat gets the planned amount.

Want more on fish oil itself? Our fish oil for cats guide covers how it works and how owners give it.

Why cod liver oil needs extra caution

Cod liver oil does carry omega-3s. But it also brings vitamin A, and that is the problem.

VCA says vitamin A poisoning in pets most often happens when they eat raw liver, cod liver oil or other supplements.

In addition, the Today's Veterinary Practice review warns that supplements can lead to nutrient excess. It names vitamins A and D as the main concerns.

So cod liver oil is not a good default when you look for the best omega 3 for cats. Use it only when your vet picks it for a clear reason.

For the full story, read our cod liver oil for cats guide.

Side effects to weigh with the best omega 3 for cats

Even a well-made oil can cause trouble. VCA lists stomach upset, a fishy odor, slower wound healing and an oily coat as common side effects.

Serious signs to report

VCA also flags rarer but serious effects. These include unusual bruising or bleeding, which VCA highlights in cats, and pancreatitis.

PetMD adds that high doses can bring diarrhea, vomiting and lethargy. It also notes fish oil can change blood clotting.

When to be careful

• Your cat takes blood thinners, NSAIDs such as meloxicam or robenacoxib, or doxorubicin.
• Your cat has a clotting disorder, diabetes or a history of pancreatitis.
• Surgery is coming up. A dvm360 summary of a 2013 review says platelet effects showed little clinical impact so far, but still urges caution around surgery.
• Your cat is overweight, because oils add calories. Even the best omega 3 for cats adds to the daily total.

The 2020 dosing review also lists weight gain and drug interactions among possible effects. Plus, the dvm360 summary says there is not enough data to set a safe upper limit for cats.

Freshness, contaminants and the best omega 3 for cats

EPA and DHA can oxidize. That is why makers often add vitamin E, per the dvm360 summary.

VCA notes some fish oil sources carry a high risk of heavy metal toxicity. Also, the dvm360 summary says heavy metal and PCB exposure may be higher in cats that eat fish-based diets.

So ask any maker about contaminant testing. A clear answer is part of what makes the best omega 3 for cats. Then store the oil somewhere cool and dry, out of the light, as VCA advises.

Check the diet before you buy the best omega 3 for cats

Before you add anything, look at the food bowl. Some diets already include extra omega-3s.

For example, VCA says kidney-support diets already have higher omega-3 levels. Cornell notes that some skin diets already include fatty acids and vitamin E.

So adding even the best omega 3 for cats on top could mean more than your cat needs. Cornell also warns that too much can cause harm, and suggests you check the amount with your vet.

• Read the food label for fish oil, EPA or DHA.
• Ask the food maker for omega-3 levels if they are not listed.
• Bring both the food and supplement labels to your vet.

Curious which foods carry these fats? See our omega-3 foods for cats guide.

Dose: why your vet sets the amount

You will not find a dose chart in this guide, and that is on purpose. VCA tells owners to follow their vet's instructions for fish oil.

Also, the 2020 dosing review notes that data on omega-3 supplements for cats are scarce. PetMD likewise advises giving fish oil only under vet guidance.

VCA adds that supplements may interact with other medicines, and that your vet can help you pick a reputable maker. So the vet visit is part of choosing, not an extra step.

Be patient with results

VCA says the full effects of fish oil may take several weeks. For skin, Cornell notes a response may take 7 to 30 days.

Cornell also says fatty acid supplements are not 100 percent effective. So keep your vet in the loop if you do not see a change.

Use the checklist to find the best omega 3 for cats

Now put the checks to work on any product, ours included. Pick up the tub and go down the list.

1. Is the source marine, such as fish or krill oil?
2. Does the label show mg of EPA and DHA per serving?
3. Will the maker explain its QC and contaminant testing?
4. Has the company passed the NASC audit, and do you know its limits?
5. Does the form suit your cat?
6. Is it free of cod liver oil, or did your vet approve it?
7. Have you reviewed side effects, medicines and health history?
8. Did you check the food and get a dose from your vet?

A product that clears every point is a strong candidate for the best omega 3 for cats. Still, the final call belongs to you and your vet.

WSAVA says supplements need careful review for both effect and safety. It also suggests you talk to your vet first.

If you want the wider picture on omega-3 and omega-6 fats, read our omega fatty acids for cats guide.

Related guides: Omega-3 for cats · Fish oil for cats · EPA and DHA for cats

Key Terms Explained

• EPA: Eicosapentaenoic acid, a marine omega-3 fat that cats need from their diet.
• DHA: Docosahexaenoic acid, a marine omega-3 that usually travels with EPA in fish and krill oil.
• ALA: Alpha-linolenic acid, the plant omega-3 in flaxseed. Cats convert almost none of it to EPA.
• Delta-6 desaturase: An enzyme that helps turn ALA into longer omega-3s. Cats have low activity of it.
• NASC seal: A mark for companies that passed an on-site facility audit by the National Animal Supplement Council.
• Oxidation: Breakdown of oils by oxygen. Makers often add vitamin E to protect EPA and DHA.

This article is for general education and is not veterinary advice. These statements have not been evaluated by the Food and Drug Administration. Kittysum products are not intended to diagnose, treat, cure or prevent any disease.