Why milk upsets most cats
Milk contains a natural sugar called lactose. To digest it, the body needs an enzyme called lactase. Kittens make plenty of lactase, because their first food is their mother's milk.
After weaning, most cats make much less lactase. Their bodies don't expect milk any more. So when an adult cat drinks cow's milk, much of the lactose isn't broken down. It passes into the gut, where it draws in water and gets fermented by gut bacteria. That's what causes the trouble.
This is called lactose intolerance, and it's very common in adult cats. Some cats handle small amounts better than others, but there's no easy way to know in advance which group your cat is in.
Signs milk has upset your cat
Signs usually show up within hours of drinking milk:
- Diarrhoea or loose, smelly poo
- Gas and a rumbling tummy
- Vomiting
- Stomach discomfort, such as restlessness or a tense belly
- Using the litter tray more often, or having accidents outside it
Cats hide discomfort well, and some even purr while they feel unwell, so the litter tray is often the first clue. Mild cases usually settle once the milk stops. Call your vet if diarrhoea lasts more than a day, there's blood in it, your cat is vomiting repeatedly, or your cat seems tired or stops eating. Diarrhoea in a kitten always needs a vet's advice quickly, because kittens dehydrate fast.
What about cream?
Cream contains less lactose than milk, but it's very high in fat and calories. A saucer of cream adds a lot of calories to a cat's day, which adds up to weight gain over time. Fatty treats can also upset the stomach. The old picture of a cat lapping cream is a nice image, not good nutrition.
Milk and dairy at a glance
| Drink or food | Is it OK for cats? |
|---|---|
| Cow's milk (whole or skimmed) | Better not. Lactose causes upsets in many cats |
| Cream | Better not. Less lactose, but very fatty |
| Goat's milk | Better not. It still contains lactose |
| Plant milks (oat, almond, soy) | Not recommended. Not made for cats and some have added sugar |
| Lactose-free cat milk | Fine as an occasional treat |
| Kitten milk replacer | Yes, for kittens that can't feed from their mother |
| Fresh water | Yes, always |
What kittens need
Kittens should drink their mother's milk, ideally until they're weaned at around 8 weeks. If a kitten is orphaned or the mother can't feed it, use a kitten milk replacer made for cats, and ask your vet how much and how often to feed.
Cow's milk doesn't match the nutrients in a mother cat's milk, and it can cause diarrhoea. In a young kitten, diarrhoea can quickly lead to dangerous dehydration. If you find a very young kitten, contact a vet or a local cat rescue for advice.
Lactose-free cat milk as a treat
Pet shops sell milk made for cats with the lactose removed or reduced. Most cats tolerate it much better than cow's milk, and many love it. Treat it like any other snack, though. It has calories, so a small amount now and then is plenty, and it should never replace water.
If your cat has a sensitive stomach, is overweight or has a health condition, ask your vet before adding it.
Water is what cats really need
Domestic cats come from desert-dwelling ancestors that got much of their water from their prey. Many cats today still have a fairly low drive to drink. That matters, because a cat that doesn't take in enough water may be more likely to have urinary and kidney problems.
Cats that eat only dry food get very little water from their meals, so they need to drink more to make up for it. Signs to mention to your vet include fewer or smaller urine clumps in the litter tray than usual, hard, dry poo, or a cat that seems quieter and less interested in food. Straining in the litter tray, especially in a male cat, needs a vet urgently.
How to help your cat drink more
- Try a water fountain. Many cats prefer moving water, and a fountain keeps it fresh and cool.
- Use wide, shallow bowls. Many cats seem to prefer bowls where their whiskers don't touch the sides. Ceramic, glass or stainless steel bowls are easy to keep clean.
- Fill bowls to the brim. Some cats don't like putting their head deep into a bowl.
- Place water away from food. In the wild, cats don't drink next to their food. Set water a little apart from the food bowl, and well away from the litter tray.
- Put out more than one bowl. A few water stations around the house make drinking easier, especially in multi-cat homes.
- Feed some wet food. Wet food is mostly water, so it's an easy way to add moisture to your cat's diet.
- Change the water daily. Fresh water tastes better than water that's been sitting out.
If your cat suddenly drinks much more water than normal, see your vet. Increased thirst can be an early sign of kidney disease, diabetes or an overactive thyroid.
FAQ
Is a little milk OK for cats?
A lick is unlikely to harm most cats, but many get diarrhoea even from small amounts. There's no benefit, so it's best avoided.
Can kittens drink cow's milk?
No. Cow's milk doesn't have the right balance of nutrients for kittens and can cause diarrhoea, which is dangerous for them. Use a kitten milk replacer if a kitten can't feed from its mother.
Can cats have lactose-free milk for people?
It's gentler on the gut than normal milk, but it's still fatty and not made for cats. A lactose-free milk made for cats is the better choice as an occasional treat.
Can cats eat cheese or yogurt?
Hard cheese and plain yogurt contain less lactose than milk, so a tiny amount may be tolerated. They're still fatty, though, and your cat doesn't need them.
Why do cats love milk if it's bad for them?
Milk is rich in fat and protein, which cats find tasty. Liking something doesn't mean their gut can handle it.
This article is general information, not a replacement for advice from your vet.
