How to Add Oil to Cat Food: A Step-by-Step Guide

Updated November 1, 2026 · 6 min read · General care information, not veterinary advice

Why people add oil to cat food

Owners add oil to a cat’s food for a few everyday reasons: to make a meal smell more tempting, to help a powder or topper stick to kibble, or as part of a daily routine with a product made for pets. Sometimes a vet suggests a specific oil, such as fish oil, for a specific reason.

Whatever the reason, the method is the same: small amounts, measured, introduced slowly. Cats are small animals with small calorie needs, and fat is the most concentrated source of calories there is.

Step 1: Check with your vet first

Cornell’s Feline Health Center advises that supplements should never be given to a cat without a veterinarian’s approval, and that when a cat eats a balanced and complete diet, supplements are usually not necessary (Cornell Feline Health Center). Veterinary nutrition sources also say high-fat feeding should be used with caution in pets that are overweight, have high blood fats, or have pancreatitis (Today’s Veterinary Practice).

Ask first if your cat:

• Takes any medicine
• Has a health condition, especially of the gut, pancreas or liver
• Is overweight
• Is a kitten, or is pregnant or nursing
• Has recently had surgery or has a wound that is healing

The last point is there because omega-3 supplements can affect blood clotting and wound healing (Today’s Veterinary Practice).

Step 2: Choose the right oil

• Use a product made for pets, with a cat serving on the label. Human supplements are dosed for people and may contain extra ingredients.
• Know what the oil brings. Fish oil supplies the omega-3s EPA and DHA (PetMD). Plant oils such as hemp seed or flaxseed supply omega-6 linoleic acid and the plant omega-3 ALA, which cats convert into EPA very poorly (Today’s Veterinary Practice).
• Skip cooking fats. Bacon grease, butter and fat trimmings are not a plan. The ASPCA warns that fatty foods can cause vomiting, diarrhea and possibly pancreatitis in pets (ASPCA).
• Never use essential oils. Essential oils are not food oils and are not for adding to a cat’s food.

Step 3: Work out a sensible amount

Here is why the amount matters so much. Every gram of fat carries 9 calories (U.S. FDA). A normal, neutered 10-pound adult cat needs only about 262 calories a day, and an 8-pound cat about 221 (Animal Medical Center of Chicago).

A level teaspoon of oil weighs roughly 4.5 grams, which works out to about 40 calories. For that 10-pound cat, one teaspoon would be around 15% of the whole day’s calories. VCA Animal Hospitals says treats and extras should stay under 10% of daily calories, and aiming for 5% is safer (VCA).

The teaspoon figure is our own arithmetic: about 4.9 mL in a teaspoon, times a typical oil density of about 0.92 g/mL, times 9 calories per gram.

So the rule of thumb is simple: think in drops, not spoons. Pet oils for cats usually come with a dropper and a cat serving of a fraction of a dropper. Follow the label, or the amount your vet gives you.

Step 4: Start low and go slow

Extra fat can upset the stomach. Possible side effects of omega-3 supplements include vomiting and diarrhea (Today’s Veterinary Practice), and any new food can put a picky cat off. A gentle start:

If your cat vomits, gets diarrhea or refuses the meal, stop and talk to your vet. And remember that an adult cat who eats nothing for 24 hours needs a vet visit, whatever the reason (Cornell).

Step 5: Mix it in the right way

With wet food

1. Put a small first portion, a tablespoon or so, in the bowl.
2. Add the drops and mix well so the oil disappears into the food. Pâté-style food hides it best.
3. Let your cat finish that portion, then serve the rest of the meal.

Serving the food at room or body temperature can help. In a Waltham study, older cats ate the most wet food when it was warmed to body temperature, and the least when it was fridge-cold (Waltham).

With dry food

1. Measure the meal into a small bowl.
2. Drizzle the drops over it and toss with a spoon so the kibble is lightly coated.
3. Serve right away. Don’t pre-oil a whole bag; oiled kibble left sitting goes stale faster.

Straight from the dropper

Some cats will lick drops off a spoon or from the dropper tip. Never squirt oil into the back of a cat’s mouth; it can be inhaled.

Step 6: Keep it consistent

Cats like routine. The same bowl, the same spot and the same time each day make a new addition far easier to accept. Pick one meal, usually the first of the day, and add the oil there.

Step 7: Store the oil properly

Oils rich in polyunsaturated fats, such as hemp seed, flaxseed and fish oil, can go rancid with heat, light and air. Cornell notes that long storage makes fats more likely to turn rancid in cat food, and the same logic applies to the oil you add (Cornell).

• Close the cap tightly after every use.
• Keep the bottle out of sunlight and away from the stove.
• Follow the label’s storage note; some oils should be refrigerated after opening.
• Wipe the dropper clean and don’t let it touch the food.
• Smell it now and then. A sharp, bitter or paint-like smell means it’s time to throw it out.

Common mistakes to avoid

• Pouring from the bottle instead of measuring
• Starting at the full amount on day one
• Adding oil and a new food at the same time, so you can’t tell what your cat objects to
• Forgetting that oil counts toward the daily calorie budget
• Using an oil to try to fix a health problem without seeing a vet

For more on which fats cats actually need, read omega-3 for cats. If your cat is fussy at mealtime, our guide to food toppers for picky cats has more ideas.