Cats have to get taurine from their food. Dogs and people make enough of their own; cats do not, and a diet that falls short can slowly damage the retina and the heart muscle. Taurine is now added to commercial cat foods, so a cat eating a complete and balanced food made for cats is very unlikely to run short. The cats at risk are mostly those fed vegetarian or vegan diets, dog food, or home-prepared meals.
What Is Taurine Deficiency in Cats?
Taurine deficiency means a cat has less taurine than its body needs, almost always because the diet did not supply enough. As the Merck Veterinary Manual puts it, unlike dogs, cats require dietary sources of taurine.
The damage is not all alike. Retinal damage is permanent. Heart damage caused by taurine deficiency can often be reversed if it is found and treated in time.
Symptoms of Taurine Deficiency in Cats
- Vision loss and blindness: Taurine keeps the light-sensing cells of the retina, at the back of the eye, working. In a 1975 study, cats fed a taurine-deficient diet developed degeneration of these cells along with falling taurine levels in the blood and retina. Vets call the result feline central retinal degeneration. Once those cells are gone, they are not replaced.
- Heart disease: Without enough taurine, the heart muscle weakens and the heart enlarges, so it pumps poorly. This is dilated cardiomyopathy (DCM). It can lead to congestive heart failure, where fluid builds up in or around the lungs, and untreated it can be fatal.
- Reproductive problems and weak kittens: In research studies, queens (breeding females) fed taurine-deficient diets lost many pregnancies and had stillborn or low-birth-weight kittens. Kittens from deficient mothers survived less often and grew more slowly.
- Immune system changes: Experimental work found low white blood cell counts and weaker infection-fighting cell function in cats with prolonged deficiency. These are lab findings, not something an owner would see.
What you may notice at home
Early on, probably nothing. Deficiency develops slowly, and the eye and heart changes can be well advanced before a cat looks unwell. When the heart is involved, the signs are those of heart disease in general, as described by the Cornell Feline Health Center:
- fast or labored breathing
- low energy
- a poorer appetite
- sudden weakness or paralysis of the hind legs, caused by a blood clot (a known complication of cardiomyopathy in general)
If the retina is affected, you may also notice signs that your cat is not seeing well.
Fast or labored breathing and sudden hind-leg paralysis are emergencies. Take your cat to a veterinarian or an emergency clinic right away. For more on how heart failure shows up in cats, see our guide to congestive heart failure in cats.
A DCM diagnosis does not automatically mean a diet problem
Taurine deficiency used to be a major cause of DCM in cats. Since the link was found in 1987 and taurine was added to commercial cat foods, feline DCM has become much less common, and the Merck Veterinary Manual says most cats diagnosed with it today are not taurine-responsive. Your veterinarian will still ask about diet, because the taurine-responsive cases are the ones that can recover.
The Causes of Feline Taurine Deficiency
Because complete and balanced commercial cat foods have taurine added, Merck says deficiency now turns up only occasionally, mostly in cats fed noncommercial diets. The usual causes are:
- vegetarian or vegan diets
- dog food fed as a cat's main diet, since diets formulated for dogs are not built for a cat's needs
- home-cooked or home-prepared diets not formulated by a veterinary nutritionist
- baby food or other foods not meant as a complete diet for cats
Why Do Cats Need Taurine?
Taurine is usually called an amino acid. Strictly, it is an amino sulfonic acid made from the sulfur-containing amino acids methionine and cysteine. It is not used to build proteins; it works as a free molecule in tissues such as the heart muscle and the retina.
Cats cannot make enough of it, so for them taurine is an essential nutrient that has to come from the diet. That fits cats as strict carnivores. They need more protein than most mammals, and meat supplies both.
Diagnosing Feline Taurine Deficiency
Diagnosis can be tricky because signs develop over months to years; in one classic study, cats fed a diet only marginal in taurine for four years developed low blood taurine and heart muscle failure.
The diet history matters most. If your cat eats a commercial food, bring the bag or a photo of the label. If you cook at home, write down every ingredient and how you prepare it.
Testing may include:
- routine blood and urine tests, which often show no taurine-specific clue
- a blood taurine test, which your veterinarian sends to a laboratory and reads against that lab's own reference range
- an eye exam to look for central retinal degeneration
- heart tests: echocardiography (heart ultrasound) is the main test for cardiomyopathy. Chest X-rays show whether fluid has built up, and an electrocardiogram is sometimes added. A blood test called NT-proBNP can help screen for heart disease, but it does not diagnose it.
Available Treatment Options
Your veterinarian leads treatment based on the test results. It usually has two parts:
- Fixing the diet: your cat moves to a complete and balanced food made for cats, or to a home-prepared diet reformulated by a board-certified veterinary nutritionist.
- Replacing the taurine: if deficiency is confirmed or strongly suspected, your veterinarian prescribes taurine and chooses the product, the dose and how long to give it. Do not start supplements on your own. Rechecks show whether it is working.
In the 1987 study that made the link, cats with low blood taurine and failing heart muscle regained normal heart function after taurine supplementation. A cat in heart failure also needs treatment for the heart failure itself, which your veterinarian manages alongside the taurine.
Vision lost to retinal degeneration does not come back. Blind cats usually adapt well at home if you keep the furniture where it is, keep food, water and the litter box in fixed places, and block off stairs, balconies and other drops.
Prognosis
Merck notes that cats with taurine-responsive DCM have a high risk of death at first, but those that survive the first weeks, while taurine takes effect, have an excellent prognosis because the heart disease is completely reversible.
Retinal damage, by contrast, is permanent. In kittens, deficiency can also slow growth and development, one more reason pregnant and nursing queens need a complete diet.
Can It Be Prevented?
Yes. A complete and balanced commercial cat food is the simplest protection, because taurine is added to these foods.
To check a food, look for a nutritional adequacy statement on the label saying it is "complete and balanced" for your cat's life stage, such as growth or adult maintenance. The WSAVA guidelines on selecting pet foods note that foods formulated to AAFCO (Association of American Feed Control Officials) guidelines should meet its nutrient profiles, and suggest asking the manufacturer whether they employ a qualified nutritionist and who formulates their diets.
If you prefer a home-prepared diet, have it formulated by a board-certified veterinary nutritionist (ACVN in the US, ECVCN in Europe). If you are considering a vegetarian or vegan diet for your cat, talk to your veterinarian first.
Where Does Taurine Come From for Cats?
Taurine is found in animal tissues: meat, fish, seafood and organs. A UC Davis study of feed ingredients found high levels in animal muscle, especially from marine animals, while plant products had low or undetectable amounts.
Cooking matters too: in the same study, ingredients cooked surrounded by water, such as boiled meat, lost the most taurine, while baking or frying kept more. That is one reason home-cooked diets need a nutritionist rather than guesswork. Some foods people cook with are also unsafe for cats; see our list of things cats can't eat.
Wrapping Things Up
Taurine deficiency is no longer a common problem in the veterinary clinic, because once vets understood why cats need taurine, cat foods started including it. Your part is small but real. Check for the complete-and-balanced statement, be cautious with vegetarian, vegan and home-cooked diets, and call your veterinarian about breathing changes, sudden hind-leg weakness or vision problems. Breathing trouble and sudden paralysis are emergencies.
Diet-related heart disease plays out differently in dogs; our article on dilated cardiomyopathy in dogs covers that side.
Sources
- Merck Veterinary Manual: Dilated Cardiomyopathy in Dogs and Cats
- Merck Veterinary Manual: Nutritional Requirements of Small Animals
- Cornell Feline Health Center: Cardiomyopathy
- Science (Hayes et al., 1975): Retinal degeneration associated with taurine deficiency in the cat
- Science (Pion et al., 1987): Myocardial failure in cats associated with low plasma taurine: a reversible cardiomyopathy
- Journal of Nutrition (Sturman, 1991): Dietary taurine and feline reproduction and development
- Journal of Leukocyte Biology (Schuller-Levis et al., 1990): Immunologic consequences of taurine deficiency in cats
- Journal of Animal Physiology and Animal Nutrition (Spitze et al., 2003): Taurine concentrations in animal feed ingredients; cooking influences taurine content
- WSAVA Global Nutrition Committee: Guidelines on Selecting Pet Foods
This article is for general information and is not a substitute for advice from your veterinarian.
