Cats cannot make enough taurine for their own needs, so it has to come from food. A cat short of it slowly loses retinal cells and can develop a failing, enlarged heart. Complete commercial cat foods are formulated to meet taurine minimums, so the cats at risk today are mostly those eating home-prepared meals, dog food or plant-based diets without a proper supplement.
What taurine is and why cats depend on it
Taurine is a sulfur-containing amino acid. Unlike most amino acids it is not built into proteins; it circulates freely and is concentrated in tissues such as heart muscle, the retina and the brain. Most mammals make it from the sulfur amino acids methionine and cysteine.
Cats have two problems at once. Their capacity to synthesize taurine is low, and they use it to process bile: cats conjugate their bile acids with taurine but cannot synthesize enough to cover what is lost. Some of that bile taurine can be broken down by gut bacteria rather than recycled, so a steady supply in the diet is needed.
The eye problem was recognized first. By the late 1970s, veterinarians had described retinal degeneration in cats fed commercial dog food that contained little or no taurine, with blood tests confirming the deficiency. The connection with heart failure came about a decade later.
What deficiency does
Retinal degeneration
In the cats fed dog food, lesions ranged from small patches of atrophy centered on the area centralis, the part of the retina used for sharp vision, to atrophy of the whole retina. Only the cats with generalized atrophy went blind. Photoreceptors that have died do not grow back, so correcting the diet can halt further loss but will not restore sight already gone. Signs worth a veterinary eye exam include bumping into furniture, reluctance to jump, and pupils that stay wide in normal light.
Dilated cardiomyopathy
In dilated cardiomyopathy (DCM) the heart muscle thins and weakens, the chambers stretch, and the heart pumps poorly. Fluid builds up in or around the lungs, and blood clots can form in the enlarged heart. Rapid or labored breathing at rest, lethargy, hiding, poor appetite and sudden weakness or pain in the hind legs all need a vet the same day.
Taurine-related DCM can improve when the deficiency is corrected. In a group of 37 cats with moderate to severe DCM treated between 1986 and 1988, standard heart treatment was combined with taurine. Fourteen died in the first month, but 22 improved markedly and lived longer than 240 days, and most of them later came off every medication, including the taurine tablets, once their food supplied enough. One-year survival was 58%, against 13% in an earlier, retrospectively reviewed group of cats with DCM. The first weeks are the dangerous period, which is why a cat with these signs needs a vet, not just a change of food.
Cats that survived the first month of treatment for taurine-related heart failure usually stayed stable on diet alone. The app can build a feeding plan around one cat's actual diet.
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Queens fed taurine-deficient diets in long-term breeding studies had frequent fetal resorption and abortion, stillbirths and low birth-weight kittens. Kittens born to deficient mothers survived poorly and grew more slowly, had smaller brains at birth and weaning, and the survivors showed a range of abnormalities. The mothers' milk also carried less taurine.
How much a cat food should contain
The AAFCO Cat Food Nutrient Profiles set taurine minimums on a dry matter basis for both growth and adult maintenance:
| Food type | Minimum, % of dry matter | Minimum per 1,000 kcal |
|---|---|---|
| Dry (extruded) | 0.10% | 0.25 g |
| Canned | 0.20% | 0.50 g |
The canned figure is double because cats fed canned diets need more dietary taurine to keep the same blood level as cats on dry food. The bile acid study cited above found more bacterial conversion of bile acids when cats ate canned food and suggested that the change in gut bacteria may increase taurine breakdown. The same AAFCO document sets no taurine minimum for dog food. Dogs, unlike cats, normally make enough of their own.
Where taurine comes from
Taurine is an animal-tissue nutrient. An analysis of common pet food ingredients found high concentrations in animal muscle, especially from marine species, and low or undetectable levels in plant products. Cooking method changed how much survived. Meat that sat in water while cooking, as in boiling or basting, lost more taurine than meat that was baked or fried. A home cook who boils chicken for a cat and pours off the water is likely pouring away some of the taurine with it.
Plant-based cat foods can only meet the requirement with added synthetic taurine.
When taurine becomes a concern
- Home-prepared diets. Of 114 cat recipes collected from books and websites, 94 had enough detail to analyze, and none met all the recommended nutrient allowances. Even among the best veterinarian-written recipes taurine adequacy could not always be confirmed. A home diet for a cat needs a recipe formulated by a board-certified veterinary nutritionist, with the supplements it specifies.
- Dog food. Dog food is not required to contain taurine at cat levels, or at all. An occasional stolen mouthful does no harm, but it should not be a cat's regular diet.
- Vegetarian or vegan feeding. Plants supply essentially none. Any such diet for a cat must be complete and balanced for cats, with added taurine.
- Unbalanced raw or whole-prey feeding. Muscle meat contains taurine, but a mix that has not been formulated for cats and checked can still fall short.
A cat eating a complete commercial food labeled for its life stage is unlikely to be taurine deficient. If a cat has been on one of the diets above and shows vision or breathing changes, tell the vet about the diet; a blood taurine test can help confirm or rule out deficiency.
Sources
- Fecal bile acid excretion and taurine status in cats fed canned and dry diets. The Journal of Nutrition, 1994.
- Retinal degeneration associated with the feeding of dog foods to cats. Journal of the American Veterinary Medical Association, 1978.
- Response of cats with dilated cardiomyopathy to taurine supplementation. Journal of the American Veterinary Medical Association, 1992.
- Dietary taurine and feline reproduction and development. The Journal of Nutrition, 1991.
- AAFCO Dog and Cat Food Nutrient Profiles. Association of American Feed Control Officials, 2014.
- Taurine concentrations in animal feed ingredients; cooking influences taurine content. Journal of Animal Physiology and Animal Nutrition, 2003.
- Evaluation of the nutritional adequacy of recipes for home-prepared maintenance diets for cats. Journal of the American Veterinary Medical Association, 2019.
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