Cats Are Actually Lactose Intolerant

“I think all cats are wild. They only act tame if there’s a saucer of milk in it for them.” —Douglas Adams, Last Chance to See

In A Nutshell

Few species of animal enjoy lactose outside of infancy, and even fewer of those enjoy the lactose of another animal. As common a theme as a cat lapping at a saucer of milk might be, lactose intolerance is the norm for most of any adult mammal. Only humans are found to enjoy the milk of another animal well into their adulthood.

The Whole Bushel

Typically, mammals end up on a diet of milk in their early lives brought to them by their mother’s milk. This is often the first source of nutrition available, and “mother’s milk” also has a lot of other positive properties outside of base nutrition, such as proteins to help build the immune system. To properly handle and digest lactose our bodies have to produce its own enzyme known as lactase. Lactose is made up of two sugars, glucose and galactose, so for mammals to properly digest lactose it needs to be broken into two singular sugars, which is where lactase comes into play.

Lactase is produced in the body whenever lactose is consumed, so as long as lactose is in your diet, lactase will help you keep it all down. However, since most cats are natural carnivores, milk stops playing such a role in their diet once they are old enough to hunt and forage. Once cats move on to field mice, birds, and other local rodents, the build-up of lactase ceases. So as darling an image as a saucer of cream might be for that newly arrived feral cat, it is much safer and healthier to opt for a bowl of water.

While a lactose-intolerant cat typically won’t die from ingesting lactose, there are some troubling symptoms and complications that could arise. Upset stomach, diarrhea, and gastrointestinal cramps are the most common signs of lactose intolerance. Your cat should fully recover after the lactose has made it through digestion, so no worries there.

There is actually little harm in testing the waters to see if your cat is lactose intolerant. Giving your kitty a small amount of milk and watching for signs of arising symptoms is often regarded as safe practice. Some cats might even prefer milk over water, despite their digestive tract hating it, and for them there is a lactose-free alternative made special for cats.

As with most things, lactose intolerance can be taken on a case-by-case basis with each individual cat. Some cats that grew up with a heavy-lactose diet all their life would likely still produce the lactase needed to make milk a comfortable option for hydration. Some cats might find a preference for milk over certain tap waters, depending on the types of chemicals used in the local filtration.

Other potential dairy products should be treated similarly to milk, though some cheeses are much lower in lactose, and are even recommended by some veterinarians for slipping pills into, which allows an easier time medicating your kitty.

Most cat foods will provide your cat with the proper, square nutrition needed to be healthy. There are very few reasons to actively find out if your cat is or is not lactose intolerant, short of wanting to make your cat more comfortable with more options or preferences.

Show Me The Proof

ABC Science: Lactose intolerance
ASPCA: Feeding Your Adult Cat
Cats and Dairy: Get the Facts
NCBI: Diagnosis and management of food allergy and intolerance in dogs and cats

  • Karmala

    The title of this article is VERY misleading. Cats aren’t allergic to milk, they are lactose intolerant. Food intolerances and allergies ARE NOT the same thing. Lactose intolerance is caused by the lack of the lactase enzyme whereas an allergy is an immune-response. I’m sorry if I’m a bit picky but there is a huge difference between the two. I myself am lactose intolerant which only leads to upset stomachs and bloating if I consume diary. However, my children are allergic to dairy, their reactions are very severe. Their bodies fight immune systems fight against the protein as though it is a foreign invader. Anyway, that’s the end of my rant.

    • Check

      I’m lactose intolerant, too, and let me tell you, nothing is smellier than a lactose intolerant fart. Since I’ve stopped drinking milk, I feel better for it, and I don’t have nasty crowd parting flatulence anymore.

      • Karmala

        Hahaha. I can MORE than appreciate where you’re coming from with that one 🙂

    • Passin’ Through

      Not picky, correct. These articles are supposed to further our knowledge, not mislead us.

      You touched on it, but maybe Debra needs to write an article discussing the difference between lactose intolerance and dairy allergies.

  • Check

    I think that we are ALL not meant to drink milk. We are the only animal that drinks the milk of another animal intentionally. We are the only animal that drinks milk intentionally beyond our infancy. All other animals that drink milk would not have done so without a human helping them to do it in some way. I do not think that milk does a body good at all. You can get good calcium through other means.
    I love drinking milk, but I have since sworn it off, and I only eat anything dairy when I cook something in butter. But, that’s just my own opinion.

    • Spartachilles

      Humans did in fact use to be just as lactose intolerant, before we decided that we needed to milk animals as well as eat them.

    • Passin’ Through

      Your dietary choices are obviously your own, but I don’t like the “humans are the only animal to consume milk after infancy” argument.

      Humans are also the only animals to:

      cook food, freeze food, refrigerate food, eat processed food, eat more than one type of food at a time, eat meat and veggies at the same time, eat when we’re not hungry, eat socially, etc.

      When it comes down to it, milk has one and only one purpose. Food. You can’t say that about anything else in the world. Everything has some other purpose, except milk. And it’s sustainable when done properly.

  • Nathaniel A.

    ” Only westernized humans are found to enjoy the milk of another animal well into their adulthood.” This could not be further from the truth, in parts of Africa, the Middle East, and Central Asia, camel and goat milk are enjoyed frequently.

    • Spartachilles

      That is exactly what it is saying. It says “milk of another animal” so it can include camel, goat, cow, etc. milk. It doesn’t say specifically “cow milk”.

      • Nathaniel A.

        I took offense at the adjective “westernized”, and made the case that people in parts of Africa, the Middle East, and Central Asia are not westernized.

        • Spartachilles

          Sorry, I misunderstood. I get what you mean now, and I see why you took offense.

      • lbatfish

        I think what Nathaniel was getting at was the first three words that he quoted: “Only westernized humans”

      • Andy West


    • TheMadHatter

      This is listverse/knowledgenuts. Every article has to say something about how bad westerners are. Common knowledge there. But the articles are too fascinating to just stop reading, so we deal with it.

    • GODD

      Those are sub humans.

      • OC

        This from someone who gives his dog open-mouthed kisses and truly believes it’s not bestiality.

  • Atlas

    Another fact; cats are 10 times more adorable while drinking milk.

    • Andy West

      And misjudging distances and heights.

      • Atlas

        Cats are just plain adorable while doing anything.

  • JRHatt

    I had a cat that loved milk. If he saw me with a glass of milk he would bother me until I gave him some. Another cat loved ice cream.

  • Yep. We give my cat milk made for felines because she loves it as a treat, but every day we have to medicate her for an over active thyroid and a heart murmur… Which is where the cream cheese comes in. She spits out the pill if you just try to hold her mouth shut for a minute or two; even when we see her swallow, we find a pill on the floor later on.

    Cheese is the only way she’ll take it; luckily, the small amount we give her doesn’t cause any symptoms and it’s a stress-free way to medicate her… For both of us. Pfft.

  • Pawesl

    Most humans are lactose Intolerant as well and plenty of them dont even know it.

  • Ron

    My kitten Kitcat died because I fed her milk. She died in my bed. Im sorry, Kitcat.

  • ucing ker nginum susu