Can cats drink milk? The saucer of milk myth and what really happens
The cat with its saucer of milk is a storybook image, and like many storybook images it does not match the biology. Most adult cats tolerate cow’s milk badly. It is not poison, but it is not an innocent treat either, and for a kitten it can be dangerous.
Where the idea comes from
For centuries, cats on farms and in country houses lived on the mice they caught and whatever they were given, and milk was what there was. Cats like it, because it smells of fat and protein, and they drink it eagerly, so the habit was passed down and made its way into stories, cartoons and films. But a cat drinking something happily does not mean it agrees with it, just as with us. And in the case of milk, it does not particularly agree with most adult cats.
The problem is lactose
Kittens produce lactase, the enzyme that digests lactose, the sugar in milk, because they need it to suckle. When they are weaned, between four and eight weeks of age, most of them lose much of that ability, as happens in nearly all mammals. When an adult cat drinks milk, the undigested lactose reaches the large intestine, where it ferments and draws in water. The typical result is wind, a bloated belly, soft stools or diarrhoea in the hours that follow. Some cats tolerate it a little better than others, but there is no way of knowing except by trying, and it is not worth it.
And calories too
A saucer of whole milk, about a hundred millilitres, has around 60 kilocalories. For a 4 kg (9 lb) cat that needs about 190 a day, that is almost a third of what it should eat, in a single saucer. If you give it every day on top of its normal portion, weight gain is almost certain. Cream is even worse: a huge amount of fat in a very small quantity, and in susceptible cats it can contribute to digestive or pancreatic problems. If your cat has milk every day and is overweight, you already have part of the explanation.
What about lactose-free milk or “cat milk”?
Lactose-free milk for people and the special cat milks sold in pet shops and supermarkets solve the digestive problem, because the lactose has already been broken down. Most cats tolerate them well. But they are still a product with calories, often comparable to ordinary milk, and they are almost always complementary foods, in other words a treat, not a meal. If you want to give your cat that pleasure, do it now and then, in small amounts, and take those calories off its daily portion. Water is still what it should drink.
Cheese, yoghurt and other dairy
Hard, aged cheeses contain very little lactose, because it is lost during ripening, so a small piece does not usually cause digestive problems. The drawbacks are the salt and fat, and how addictive many cats find it. As an occasional treat, a piece the size of a chickpea is fine. Plain unsweetened yoghurt has a little less lactose than milk and some cats tolerate it by the teaspoon, but it provides nothing their food does not already contain. And never yoghurts with sugar, sweeteners, chocolate or fruit, or ice cream, because of the sugar and the chance they contain a toxic ingredient.
If your cat already drinks milk and it agrees with it
Some cats have had a little milk for years without any problem, and their owners wonder whether they should stop it. If there is no diarrhoea, no wind, the cat is a healthy weight and the amount is small, it is not an emergency. But it is worth switching to lactose-free, cutting it back to an occasional thing and counting its calories. And if the cat has habitually soft stools, milk is the first thing to remove before looking for other causes: it is surprising how many mild chronic diarrhoeas clear up with that alone.
The serious case: an orphaned kitten
There are no grey areas here. If you find a kitten only a few weeks old without its mother, do not give it cow’s milk, goat’s milk or supermarket milk for adult cats. Its composition is very different from a queen’s milk, with less protein and fat and more lactose, and it can cause diarrhoea that in such a small animal leads to serious dehydration within hours. What it needs is kitten milk replacer, sold at veterinary clinics and pet shops, made up according to the instructions and given with a bottle or syringe, with the kitten on its tummy, never on its back like a human baby.
What to do while you get the right milk
If it is night-time or a bank holiday and you have no milk replacer, the priority is keeping the kitten warm, because a cold kitten cannot digest and feeding it in that state can be dangerous. Wrap it in a towel with a bottle of warm, not hot, water beside it. A few hours without food, in a kitten that was healthy, are less dangerous than the wrong milk. Find an emergency clinic, which usually stocks milk replacer, and ask for advice on how often to feed, which for very young kittens is every two or three hours, through the night as well. The article on what to do if you find a kitten has the full step-by-step guide.
If it likes it so much, why does it upset it?
It is a logical question, and the answer says a lot about how cats work. What attracts a cat to milk is the fat and protein, which its nose picks up straight away, not the sugar: cats cannot taste sweetness, because they lack the receptor that detects it. Its instinct tells it this is valuable food, and its instinct knows nothing about lactose, which only becomes a problem hours later, in the gut. Many owners do not connect the diarrhoea or wind during the night with the saucer in the afternoon. A cat asking insistently for something is no sign that it is good for it, just as with ham or creamy sticks: it is a sign that it smells like something that, in the wild, was worth eating.
What your cat should drink
Water, fresh and clean, in wide bowls away from its food and litter tray. And if you want it to drink more or to give it something special, there are better options than milk: wet food with a little added water, homemade stock from boiled chicken without salt, onion or garlic, or a water fountain if it likes moving water. Milk can be an occasional, lactose-free treat. What it should not be is a habit, and still less a kitten’s food.
Most adult cats do not digest lactose well, and milk gives them wind or diarrhoea as well as plenty of calories. Lactose-free or “cat” milk is an occasional treat. Never give an orphaned kitten cow’s milk: only kitten milk replacer.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.