Key points
- Cats are obligate carnivores. Their nutritional requirements are not a smaller version of a dog's, and several nutrients they need cannot be made from plant precursors the way other mammals make them.
- Taurine is the clearest example. Cats cannot synthesise enough of it and must obtain it from their diet. Complete commercial cat foods have been fortified with taurine since the late 1980s.
- Cats also convert very little beta-carotene into vitamin A, and cannot make arachidonic acid from plant oils. Both have to come from animal sources.
- A cat eating a complete, properly formulated food is already receiving the nutrients it needs. Supplements are worth considering for specific circumstances, not as routine insurance.
- More is not better. Several nutrients cats need, vitamin A among them, accumulate in the body and can cause harm at high intakes.
- Speak to your vet before adding anything to your cat's routine, particularly if your cat is on medication, has a diagnosed condition, or is eating a raw or home-prepared diet.
Cats are not small dogs, and they are certainly not small humans. They are obligate carnivores, which means their metabolism evolved around a diet of animal tissue and has lost several biochemical shortcuts that other mammals still have.
That has practical consequences for anyone thinking about supplements. Some nutrients a cat needs cannot be manufactured internally from the building blocks that work in other species. Others accumulate to harmful levels if given in excess. And most cats eating a good complete food are already well provided for, which makes the question less "what should I add" and more "is there a reason to add anything at all".
Start with your vet
This is the first step rather than a footnote at the end.
If your cat is unwell, losing weight, drinking more than usual, grooming excessively, limping or behaving differently, that needs veterinary assessment rather than a supplement. Many of the signs owners try to address nutritionally have medical causes that are treatable when caught early.
The same applies if your cat is already on medication, has a diagnosed condition, or is pregnant. And if you feed a raw or home-prepared diet, a conversation with your vet about formulation is worth far more than any individual product, because that is where genuine nutritional gaps tend to appear.
Why taurine matters more in cats than in anything else
Taurine is an amino acid involved in bile salt formation, cardiac muscle function and retinal function. Most mammals make enough of it from cysteine and methionine. Cats do not. They have limited synthesis capacity and, unlike other species, they continue to lose taurine through bile even when intake is low.
This was discovered the hard way. In the 1970s and 1980s, cats fed diets low in taurine developed dilated cardiomyopathy and retinal degeneration. Once the link was established, taurine fortification of commercial cat food became standard, and both conditions became far less common.
The practical upshot is reassuring. If your cat eats a complete commercial food that meets FEDIAF or equivalent standards, taurine is already in it at the required level. The cats at genuine risk are those on unbalanced home-prepared or raw diets, or on dog food, which is not formulated for feline taurine requirements.
Do not supplement taurine on your own initiative. If you feed a non-commercial diet, ask your vet or a veterinary nutritionist to assess it properly.
Two more things cats cannot do
Vitamin A. Most mammals convert beta-carotene from plant foods into retinol. Cats lack sufficient activity of the enzyme that performs that conversion, so they need preformed vitamin A from animal tissue. This also means vitamin A is one to be careful with, because it is fat-soluble and accumulates. Excessive intake, classically from feeding large amounts of liver, causes skeletal problems over time.
Arachidonic acid. Other species make this fatty acid from linoleic acid found in plant oils. Cats have very limited ability to do so and need a direct animal source.
Cats also convert ALA, the plant form of omega 3 found in flaxseed, into EPA and DHA very inefficiently. Where omega 3 is concerned, marine sources do something that plant sources largely do not.
Ingredients commonly found in cat supplements
These are descriptions of what each ingredient is and where it comes from, not statements about what it will do for your cat.
Omega oils
Fish oils supply EPA and DHA directly. Flaxseed and other plant oils supply ALA, which cats convert poorly, so the source matters more in cats than it does in humans or dogs.
Petabolics Omega 3-6-9 is a fish oil complex providing a combination of omega 3, 6 and 9 fatty acids.
Commonly considered for: cats on diets low in marine oils, and older cats, in both cases in discussion with a vet.
Biotin
Biotin is a water-soluble B vitamin, also known as vitamin B7, involved in the metabolism of fats, carbohydrates and protein. It occurs naturally in liver, egg yolk and fish. Raw egg white contains avidin, which binds biotin and prevents its absorption, which is one reason raw egg is not recommended as a regular part of a cat's diet.
Petabolics Biotin is a liquid biotin preparation with potassium carbonate.
Vitamin B12
Vitamin B12, or cobalamin, is a water-soluble vitamin found in animal tissue. Absorption depends on intrinsic factor, which in cats is produced almost entirely by the pancreas rather than the stomach. This is why B12 status is something vets sometimes investigate in cats with digestive or pancreatic problems, and why low B12 in a cat is a finding to discuss with a vet rather than something to correct independently.
Petabolics Vitamin B12 is a liquid cyanocobalamin preparation.
Magnesium
Magnesium is a mineral involved in normal muscle function and in the maintenance of normal bones and teeth. It is present in meat, fish and grains.
Magnesium intake in cats is a subject vets take a specific interest in, because it interacts with urinary mineral balance. That makes it one to raise with your vet rather than add independently, particularly for any cat with a history of urinary problems.
Petabolics Magnesium is a liquid magnesium preparation.
Hemp oil
Hemp seed oil is a plant oil pressed from the seeds of Cannabis sativa. It contains linoleic acid and alpha-linolenic acid along with vitamin E. It is a source of fatty acids and nothing more: hemp seed oil is distinct from CBD products, which for animals are regulated as veterinary medicines in the UK.
Petabolics Hemp Oil is a natural hemp seed oil.
When owners typically look at supplements
Certain circumstances prompt the question more than others.
Senior cats. Appetite, absorption and body condition all change with age. Older cats also develop conditions that present gradually, so a vet check is the right first move rather than a product.
Indoor cats. Activity levels and routine differ, but a complete food is still formulated to meet requirements.
Picky eaters. A cat that has genuinely stopped eating, or is eating much less than usual, needs veterinary attention promptly. Cats that go without food for even a few days are at risk of hepatic lipidosis, a serious liver condition. This is not a wait-and-see situation.
Home-prepared and raw diets. This is where real nutritional gaps occur, and where professional formulation advice is genuinely necessary.
Seasonal shedding. Normal in most cats. Sudden coat changes, bald patches or excessive grooming are not, and warrant a vet visit.
How to introduce a supplement
Once you and your vet have agreed something is worth trying:
- Introduce one product at a time so you can tell what is doing what.
- Start at the lower end of the recommended amount and follow the label.
- Give it time. Coat and condition changes take weeks rather than days.
- Stop and speak to your vet if you notice any change in appetite, litter tray habits or behaviour.
- Store products as directed. Oils in particular degrade when exposed to heat and light.
Frequently asked questions
Does my cat need supplements if it eats complete cat food?
Usually not. Complete foods meeting FEDIAF or equivalent standards are formulated to supply the nutrients cats require, including taurine. Supplements are worth discussing for particular circumstances rather than as routine.
Can I give my cat dog supplements?
No. Dog products are formulated for a species with different requirements, and some ingredients safe for dogs are not appropriate for cats. Use products formulated for cats.
Is it possible to give a cat too much of a vitamin?
Yes. Fat-soluble vitamins, vitamin A in particular, accumulate in the body. Excess causes real harm over time. This is why following the stated amount matters and why stacking multiple products without advice is unwise.
Why is taurine specifically a cat issue?
Cats have limited ability to synthesise taurine and continue losing it through bile regardless of intake. Deficiency causes cardiac and retinal disease. Commercial cat foods are fortified accordingly.
Should I supplement taurine myself?
Not without veterinary advice. Complete foods already contain it. If you feed a raw or home-prepared diet, have the diet assessed rather than adding taurine in isolation.
My cat has stopped eating. Should I try a supplement?
No. Contact your vet. Cats that stop eating can develop serious liver complications quickly, and reduced appetite is a symptom worth investigating rather than working around.
The short version
A cat on a good complete food is already well fed. Supplements have a place in specific situations, and your vet is the right person to identify whether yours is one of them. What makes cats different is not that they need more, but that what they need is narrower and less forgiving than it is in other animals.
Supplements are not a replacement for veterinary care.
