Feeding & Nutrition

My neighbour's cat, Biscuit, used to wait on my back step every morning like clockwork. I'd pour a little saucer of milk, proud of myself for being the kind neighbour. Biscuit would lap it up, purr, and leave. For two years I thought I was doing something nice. Then my vet asked one question that stopped me: "When did you last see a cat milk a cow?"

Turns out most cats lose the enzyme that digests lactose sometime after they're weaned. Kittens make plenty of lactase while they're on their mother's milk. By the time they're grown, that enzyme has mostly packed up and gone home. Give an adult cat a bowl of cow's milk and you've handed them a serving of sugar their gut can no longer break down.

The result is not pretty. Biscuit, I later realised, had been leaving little soft presents on the neighbour's doormat for months. I blamed the weather. It was the milk. Children's books and cartoons are full of cats and saucers, which is probably why so many of us grow up certain it's a treat. The stories got there first, and the biology never got a word in.

What actually happens in the bowl

Cow's milk is roughly four to five percent lactose. A cat with low lactase ferments that sugar in the large intestine instead of absorbing it. The byproducts pull water in, the gut gets gassy, and you get the squirts. Some cats tolerate a few licks with nothing worse than a burp. Others, like Biscuit, get loose stools for a day. A few vomit. It's a lottery you don't need to play.

There's a second problem people ignore. Whole milk is fat-heavy and calorie-dense for a creature that weighs four kilos. A saucer a day is the feline equivalent of a person drinking a milkshake before every meal and then wondering why the trousers don't fit. It pads on weight without adding anything a balanced diet doesn't already give. My own cat, who shall remain nameless, once put on half a kilo in a month from precisely this habit before I caught it.

None of this means milk is poison. A lick of your cereal bowl won't send a cat to the clinic. The trouble starts when the saucer becomes a habit, or when a well-meaning owner swaps it in for real nutrition because "the cat loves it."

The things people pour instead

If you want to treat a cat, water is the unglamorous hero. Most cats don't drink enough, and a cat water fountain got Biscuit drinking more in a week than a year of still bowls. The moving water seems to trip some ancient "this is a stream, it's safe" switch in their heads. I was sceptical until I watched her ignore a fresh bowl and march to the fountain like it owed her money.

There are lactose-free "cat milks" on the shelf, formulated without the sugar. They're a fine occasional treat, but read the back: some are just water, skim powder, and flavour. They are not food. They're a novelty, like a dog biscuit shaped like a bone. I bought one branded bottle, Biscuit sniffed it once and walked off, which told me everything about how much she'd actually missed dairy.

Plain, unsalted bone broth, cooled and with the fat skimmed, is something I keep in the fridge. A spoonful over dinner wakes up a cat that's gone off its food, and there's no lactose to worry about. Just never use stock cubes from the supermarket aisle — they're loaded with onion and salt, and onion is the one thing you do not feed a cat. I learned that rule the expensive way, reading an ingredients list at midnight after a panic.

And kittens? They need milk, but it's their mother's, or a proper kitten formula from the vet if she's not around. Cow's milk is too poor in the right fats and too rich in the wrong sugars for a baby. I learned that the hard way fostering a litter that arrived without a mum, when the rescue handed me a packet of formula and a syringe and said "not a drop of dairy." They thrived. The cow's milk would have made them sick.

A simple test, if you must

If you're curious whether your cat tolerates a dab of dairy, give a teaspoon and watch for twenty-four hours. Firm litter-box output and no gas means you've got one of the lucky few. Loose stools means the answer is no, and the tradition ends there. Don't escalate the amount to "build tolerance" — you can't train a missing enzyme back into existence, any more than you can teach a cat to photosynthesise.

I still see Biscuit on the step. I fill the saucer with water now, and she drinks it without complaint. The soft presents stopped. Sometimes the kindest thing you can do for a cat is ignore the tradition and pour the boring stuff.