My cat seems to enjoy a bowl of cow's milk. I have noticed some runny stools, since I have been giving him milk. Could the milk be causing this?

We are thinking about getting another cat (as a kitten), would it be advisable to feed the kitten milk and why?


1 Answer 1


No, you should not if you're seeing signs of runny stools!

Just like humans, cats can be lactose intolerant. While some cats seem to handle milk fairly well, many get diarrhea from it. Some cats may also get an upset stomach, or it may even trigger vomiting.

From the WebMD article:

Most of us have probably given our cats a bit of milk and never noticed a problem. That’s because some cats tolerate milk just fine, Wynn tells WebMD.

How can you tell? Try offering your cat a tablespoon or two of milk. If you don’t see symptoms within a day, chances are good your cat will do fine with milk as an occasional treat.

Still, most veterinarians don't recommend it. Cats don’t need milk, and the potential problems outweigh the potential benefits.

Remember that treats of all sorts -- such as tuna, meat, cheese, or other “people foods” -- should make up no more than 5% to 10% of your cat’s diet. The rest of your cat's calories should come from a high-quality, nutritionally complete cat food.

Note that some cats apparently do not have a problem digesting milk, even as an adult. There is speculation that this may be an evolutionary response to the domestic relationship between cats and humans, due to human cultivation of cows as a food source:

However, early during the domestication of sheep, cattle, and goats, humans appreciated the milk of these animals as an extremely valuable food resource. Interestingly, as humans began using dairy products in their diet, nature selected for those individuals in whom production of lactase persisted into adulthood, which gave them an advantage over those who could not digest lactose but instead became ill from consuming milk. Lactase Persistence is a gene. Those individuals in whom the gene expressed itself were healthier and longer-lived due to the superior nutrition received from milk. They were more likely to have more children, and so the lactase persisting gene got passed on and spread. Lactase persistence is most prevalent in people of European descent, because very early in this period, cattle spread with humans from the “Fertile Crescent” into Europe with the Neolithic Expansion. The gene mutation, enabling Lactase production into adulthood, originally occurred in the region of today’s Austria and Hungry, and began spreading 7500 years ago from there throughout Europe – especially northern Europe.

By nature, cats are attracted to foods rich in protein and fat from animal source. 9000 years ago, milk and simple dairy products would have caught their attention as much as these foods do today. Thousands of years ago, people most likely delighted in gaining an animal’s affection by offering it food in the same way as we do today. By which other way could domestication have occurred? Cats may have been exposed to milk and dairy product as food past their infancy for nearly as long as people have. The possibility exists, that some cats have developed Lactase Persistence in a similar way that people have. In fact, there are some strong hints made among those who study evolution, that domestic cats , especially from European descent, have. Such a suggestion was re-published, for example, by Jerry A. Coyne, Ph.D, Professor in the Department of Ecology and Evolution at the University of Chicago in an entry in his blog.

  • 1
    @Skippy That's what I had thought, but according to the article I linked: "But as we grow up, it’s normal for people and cats to begin producing less lactase. Less lactase means less ability to digest lactose. The result may eventually be lactose intolerance." That implies that cats do produce lactase, at least as kittens. I'm now looking for other sources to get some clarification.
    – Beofett
    Oct 18, 2013 at 14:55
  • We've got one cat who positively adores ice cream - we don't give him much, but he does love to lick the bowls clean after we're done (then we rinse the bowls and put them through the dishwasher!)
    – Kate Paulk
    Oct 18, 2013 at 15:07
  • One problem may be the dosage - our bowls are huge! I give milk to my elderly cat as a treat at times, in a tiny bowl used for measuring out an ounce or so. He gets constipated at times, so a bit of softening is a bonus. And he could use some help gaining weight.
    – Oldcat
    Nov 1, 2013 at 22:36
  • Does this apply to all dairy? Is the lactose level too high in all dairy products? What about yogurt? What about the occasional lick of butter (e.g., after using butter in a recipe, before washing your hands, letting a cat lick some butter residue from your fingers)?
    – Synetech
    Dec 5, 2013 at 1:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.