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Health & Wellness

Are cats lactose intolerant?

The science behind what happens when cats drink milk.

Leaving milk out for cats is an idea that seems to have been around for ages — but is it actually safe for our pets? While you might not have thought twice about it before, it’s important to learn if cats are lactose intolerant and the science behind the answer. 

Can cats drink milk?

You might’ve seen a cat drinking milk before, but did you know that it’s actually not a good idea to give them any dairy milk? That means the next time you’re enjoying a glass, you should refrain from sharing it with them. 

“Although cats are typically drawn to milk and other dairy products, many adult cats are lactose intolerant,” Dr. Emily Singler, VMD, Fetch’s on-staff veterinarian, says. “Therefore, feeding cats any milk or cream isn't recommended.”

Why’s milk bad for cats? 

Adult cats lack the digestive enzyme that breaks down lactose (aka the sugar in milk), Dr. Singler shares. So, like some humans feel sick when consuming dairy, most felines won’t feel good after drinking it.

“As this sugar sits in cats’ intestines and ferments since it isn't properly digested, it can cause gastrointestinal upset, discomfort and diarrhea,” Dr. Singler explains. “It also adds unnecessary calories to a cat's diet and disrupts the balance of nutrients provided in a well-balanced, commercial pet food.”

Can cats drink non-dairy milk? 

Though you might be excited to offer your cat a few licks of almond milk, it’s better that you don’t. “Plant-based milks don’t contain lactose, but they still add unnecessary calories to a cat's diet and disrupt the nutrient balance,” Dr. Singler says. 

Sticking to standard cat food, treats and water is your best bet for a happy, healthy kitty.

RELATED: Here’s what to give cats for diarrhea

Can kittens drink milk?

We know the science behind why adult cats can’t drink milk, but does that mean dairy is off-limits for kittens, too? “Kittens who are young enough typically still have lactase, the enzyme needed to break down lactose in milk,” Dr. Singler says. 

That means, technically, yes, very young kittens can digest dairy milk. However, kittens are usually weaned when they’re 8 weeks old, so the window between being able to digest milk and losing that lactase is tiny. 

“After that, they don’t need to drink milk in any form,” Dr. Singler explains. “They can and should get all their nutrition from their food and only drink water. Moreover, adult cats don’t have as high of metabolism as kittens, so they can become overweight more easily with excessive calorie consumption.”

Can cats eat cheese?

Simply put: no. “All of these products contain lactose in varying amounts,” Dr. Singler adds.

And for those wondering about some of the many dairy- and lactose-free alternatives, it’s better to keep those for yourself, too. “They add extra calories to a cat's diet; therefore, none are recommended.”

So what can cats drink? 

“Kittens who are nursing or aren’t old enough to be weaned can drink their mothers' milk and/or kitten-milk replacer, which is formulated from cow's milk,” Dr. Singler explains. 

But any cat that’s been weaned (generally over 8 weeks) will be content with fresh water daily, as it provides all the hydration without any lactose or extra calories.

The Dig, Fetch Pet Insurance's expert-backed editorial, answers all of the questions you forget to ask your vet or are too embarrassed to ask at the dog park. We help make sure you and your best friend have more good days, but we’re there on bad days, too.

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