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An orange tabby cat laps a small amount of cat milk from a shallow saucer, with a larger bowl of fresh water beside it

Can Cats Drink Milk?

Most cats shouldn't drink regular cow's milk. After weaning, cats make very little lactase, the enzyme that digests the sugar in milk, so a bowl of milk can upset their stomach.

If you'd like to offer cat milk as an extra, a lactose-free one avoids that sugar. Keep it small, and keep fresh water out at all times.

The picture of a cat lapping from a saucer is a lasting one. The science behind it has a twist, and it starts with kittens.

Why is milk hard for cats to digest?

Milk's natural sugar is lactose. To absorb it, the body first needs an enzyme called lactase to split it into smaller sugars.

That's where cats come up short. The ASPCA puts it plainly: "Cats do not possess significant amounts of lactase, the enzyme that breaks down lactose in milk."

Notice the wording. It says significant amounts, not none. The Merck Veterinary Manual describes a relative lactase deficiency in cats. Their lactase activity declines after weaning, and they may become lactose intolerant.

"May" is doing real work in that sentence. Cats vary, and a small amount affects some more than others. The sources don't give a safe amount of ordinary milk for an adult cat, so there isn't one to share here.

But don't kittens drink milk?

They do, and they digest it. Merck notes that a cat's lactase activity declines after weaning, so the drop comes once milk is no longer her main food.

Here's a surprise. A 2023 review in Animal Frontiers lists cat milk at about 40 g of lactose per liter, against 47 to 51 g in cow's milk. A mother cat's milk carries almost as much lactose as the milk in your fridge.

The same review shows how different the two milks are overall:

Cat milk Cow's milk
Protein (g per 100 g) 6–9 3.1–3.2
Fat (g per 100 g) 5–13 3.6–4.0
Lactose (g per liter) 40 47–51
Energy (kcal per liter) 1,200 640

So lactose isn't foreign to a cat. It's part of her first food, and her ability to digest it drops once she's weaned. The review notes kittens are most often weaned at around 10 weeks.

Cow's milk is still wrong for kittens

Even for a nursing-age kitten, cow's milk is a poor match. Little's review in the Journal of Feline Medicine and Surgery found it lower in protein and fat than a mother cat's milk, and a poor source of taurine.

Goat's milk doesn't solve it. The same review found it has no nutritional benefits compared with cow's milk. The ASPCA also warns that cow's milk will cause stomach upset in some kittens.

A kitten without her mother needs kitten milk replacer, made to approximate a mother cat's milk. Our guide to kitten milk replacer covers how much, how often and how to bottle-feed.

What happens if my cat drinks cow's milk?

It can upset her stomach. The ASPCA says milk and other dairy products can cause digestive upset in pets, because of that missing lactase.

The Merck Veterinary Manual's guide for cat owners agrees. It says milk is not a recommended treat for cats and can upset a cat's stomach.

If your cat has already had a few laps from your cereal bowl, keep an eye on her litter box and appetite, and call your vet if anything worries you.

Call your vet promptly if your cat:

  • has an upset stomach after milk that doesn't settle
  • stops eating her normal food
  • is drinking much less water than usual
  • seems unusually quiet, weak or unwell

And if you've found a very young kitten with no mother, call a vet or shelter first. Milk from the fridge isn't the answer for her.

Can milk replace water or a meal?

No. Water comes first. The ASPCA calls water the most important nutrient, and says your cat should always have free access to fresh, clean water, with bowls cleaned every day.

The ASPCA is specific here too: milk should not be given to cats as a substitute for water. Merck suggests several water bowls around the home, and notes that wet food also adds water to a cat's day.

If your cat isn't much of a drinker, our guide on how to get a cat to drink more water has practical ideas.

Milk isn't a meal either. A cat's main food should be a complete food made for her life stage. Anything extra, milk included, belongs in the small slice the ASPCA sets aside for extras: 5% or less of her daily food intake.

What about lactose-free milk for cats?

Lactose-free milk made with added lactase has had its milk sugar broken down before it reaches the bowl. The enzyme a cat is short on has already done its work, on the sugar the ASPCA and Merck point to.

It's fair to be clear about the limits. None of the veterinary pages cited here address lactose-free milk for cats specifically, so the evidence on it is limited.

A few things are simply true of any lactose-free milk:

  • It is still dairy. Lactase changes the sugar, and the milk proteins stay.
  • It still has calories, so it counts toward that 5% of daily intake.
  • If any milk has disagreed with your cat before, skip it.

Merck also advises not giving supplements without your vet's approval, so it's worth a quick word at the next check-up.

Choosing a cat milk

If you choose to offer one, read the label. Check that it says lactose-free, see what else is in it, and start with a small amount.

Choolip's Berry Good Milk is one example. It's Grade A cow's milk made lactose-free with added lactase, ready to pour. It also provides taurine, calcium, vitamins D3 and E, omega-3 (DHA and EPA), CoQ10, glucosamine and cranberry extract.

It's sold for cats and dogs, and as an extra it sits inside the same 5% as anything else. It is not a milk replacer, so it isn't for newborn or orphaned kittens.

Questions new cat parents ask

Is cat milk for adult cats different from regular milk?

Only if the label says lactose-free. Regular cow's milk contains lactose, the part cats struggle to digest, so that word on the label is the one to look for.

Is goat milk better for cats?

Not for kittens. A review in the Journal of Feline Medicine and Surgery found goat's milk has no nutritional benefits compared with cow's milk.

Can kittens have cat milk?

Orphaned or nursing-age kittens need kitten milk replacer, not a cat milk drink. Once weaned, kittens eat a complete kitten food, with water always available.

How much milk can I give my cat?

Keep all extras, milk included, to 5% or less of her daily food intake, as the ASPCA advises. Choose a lactose-free milk and never use it in place of water.

Sources

This article is for general information and is not veterinary advice. Talk to your vet about your own cat — they know the animal in front of them.

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