A 25 g piece of cooked chicken liver carries about 3,300 IU of vitamin A. A 4 kg cat needs roughly 300 IU a day, so one small treat covers more than ten days of requirement. That is not a reason to panic, because vitamin A is stored rather than flushed out, but it is the reason liver is the one food where "a little" needs an actual number attached.
Why cats are unusually good at storing vitamin A
Cats cannot convert beta-carotene from plants into retinol, so they need preformed vitamin A from animal tissue, and the liver is where animals concentrate it. The same organ that makes liver nutritious is the organ that turns it into a dose. The classic feline disease was described in Australia in the 1950s as deforming cervical spondylosis: cats fed almost nothing but raw liver grew new bone along the neck vertebrae until the joints fused and the forelimbs weakened. Sixty years later the cases still come from home-made diets built on liver, not from commercial food.
How much vitamin A is in a piece of liver
These are USDA figures per 100 g. Cooking does not destroy retinol, which is why simmered liver reads higher than raw: the water leaves, the vitamin stays.
| Liver (raw unless noted) | Vitamin A, IU per 100 g | IU in a 25 g piece | Share of a 6,000 IU daily ceiling |
|---|---|---|---|
| Chicken, simmered | 13,300 | 3,325 | 55% |
| Chicken, raw | 11,100 | 2,775 | 46% |
| Beef, raw | 16,900 | 4,225 | 70% |
| Pork, raw | 21,600 | 5,400 | 90% |
| Duck, raw | 39,900 | 9,975 | 166% |
Beef liver braised, the form most likely to end up in a cat bowl, tests at 31,700 IU per 100 g because braising drives off even more water. The 6,000 IU column is explained in the next section.
Where the safe ceiling actually sits
AAFCO sets the adult minimum for complete cat food at 5,000 IU per kg of dry matter, which for a 4 kg cat eating about 60 g of dry matter a day works out to 300 IU daily. Published estimates of the upper safe level are much wider: a 2024 review tabulating the literature lists figures from 100,000 to 400,000 IU per kg of dry matter, and AAFCO's own legal maximum sits far above all of them. A legal maximum is a manufacturing limit for complete food, not a toxicity threshold, so treat the low end as the useful number. At 100,000 IU per kg of dry matter, a 4 kg cat's daily budget is 6,000 IU. One 25 g piece of pork liver uses 90% of it; one piece of duck liver blows through it.
What chronic overdose does to a cat
The published cases share a shape. A 9-year-old cat fed an exclusively home-made raw pork liver diet developed a limp that progressed to full forelimb paralysis over two months, plus a unilateral Horner's syndrome. Radiographs showed massive new bone from the second cervical to the sixth thoracic vertebra, narrowing the space the brachial plexus runs through. Serum vitamin A was 630 µg/dl against a reference range of 50 to 200. After the diet was switched to commercial canned food the cat regained limb function over roughly six months, but the bony change itself never reversed. A later Brazilian case, fed a raw beef liver diet, added liver fibrosis to the same spinal picture, with ankylosis from C1 to T7.
The 10% treat rule, applied to liver
WSAVA guidance keeps treats and extras under 10% of daily calories. For a 4 kg cat eating 250 kcal, that is 25 kcal: about 21 g of raw chicken liver, 18 g of raw beef liver, or 15 g of simmered chicken liver. Notice that the calorie limit is tighter than the vitamin A limit for chicken, which is the practical reason a liver treat should be small and occasional rather than a daily habit. Two 10 g servings a week supply roughly 2,200 IU for chicken and 3,400 IU for beef, comfortably inside both budgets.
Kittens and pregnant queens
Growing animals are the least forgiving group. Experimental work from 1970 showed that kittens given vitamin A in excess developed long-bone abnormalities and disturbed growth plates, and the adult spinal disease is the end point of the same process over years. A kitten's requirement per kg is higher than an adult's, which tempts owners to feed liver generously; the margin for error is still small. Queens in late pregnancy and lactation face the same arithmetic and should get liver only as a measured part of a balanced recipe.
If you suspect vitamin A excess
The early signs are easy to misread as arthritis or laziness: a cat that stops jumping onto the bed, holds its neck stiffly, resists having its head lifted for grooming, or develops a forelimb lameness that worsens over weeks rather than days. Ask for lateral radiographs of the cervical and thoracic spine; the new bone is visible long before the cat is paralysed. Serum retinol is a send-out test and supports the diagnosis, but the dietary history usually does more work than the blood test. There is no antidote. Treatment is removing the source, controlling pain, and physiotherapy, and the prognosis depends on how much neurological damage exists before the diet changes.
A liver schedule that stays inside the numbers
- Weigh it: 10 g per 4 kg of cat is a sensible single serving, not a handful.
- Frequency: two or three times a week, not daily.
- Type: chicken and beef are the mildest of the common options; pork liver carries about twice the vitamin A per gram and duck liver closer to four times.
- Count it: liver is part of the 10% treat budget, not a free extra on top of a complete food.
- Never make liver the base of a home-made diet. If you cook for your cat, follow a formulated recipe with a stated organ percentage and added calcium.
The mistake that produces poisoning is not a liver snack; it is a bowl of liver with rice, fed for months, because the cat likes it. If your cat is already on that diet, change it now and have the neck X-rayed at the next visit rather than waiting for a limp.
This article is for general information and does not replace veterinary diagnosis, examination or a formulated diet plan for an individual cat.
Terms mentioned in this article
Frequently asked
Can I give my cat chicken liver every day?
You can, but there is no nutritional reason to. A 25 g piece of cooked chicken liver supplies about 3,300 IU of vitamin A, more than ten times a 4 kg cat's daily requirement and 55% of the conservative 6,000 IU daily ceiling. Ten grams two or three times a week fits both the calorie and the vitamin A budget; a daily 25 g portion leaves no room for anything else.
Does cooking destroy the vitamin A in liver?
No. Retinol and retinyl esters are heat-stable, so simmering, frying or baking leaves the vitamin in the pan. What changes is the concentration per gram: water is driven off, so 100 g of simmered chicken liver tests at 13,300 IU against 11,100 IU for the same weight raw. Cooking makes liver slightly denser in vitamin A, not safer.
What are the first signs of vitamin A toxicity in a cat?
Stiffness rather than sudden pain: a cat that stops jumping up, holds its neck rigidly, resists having its head lifted for grooming, or develops a forelimb lameness that worsens over weeks. Radiographs of the cervical spine show new bone around the vertebrae long before paralysis. A serum retinol above the 50 to 200 µg/dl reference range supports the diagnosis, and the dietary history usually matters more than the test.
Related guides
- Cat Treat Calorie Budget: 10 Percent in 3 Conversions
- Cat Treat Calorie Cap: 10 Percent, 2 to 5 kcal
- Freeze-Dried Cat Treats: Water, Protein and the 10% Cap
- Cat Grass: 7-Day Wheatgrass and 10 cm Grazing
- How to Switch Cat Food: The 7-Day Schedule, With Grams
- Switching an 11-Year-Old Cat's Food: 7-Day Gram Plan