By Jennifer Copley (Last Updated 6 December 2011)
Many classic works of art and cartoons depict cats happily lapping cow’s milk from china bowls. Such media representations give the impression that milk is good for cats, but the reality is that for most cats, it causes stomach problems, and for kittens, cow’s milk can be deadly.
The Majority of Cats are Lactose-Intolerant
Milk contains lactose, which is particularly difficult for most adult cats (and dogs) to digest because they lack an enzyme called lactase. The undigested lactose draws water through the digestive tract and ferments in the colon, often resulting in an upset stomach and diarrhea.
Most cats like milk even though it’s not particularly good for them, and people have traditionally given it as a special treat. Some cats are able to tolerate it, so if an adult cat shows no signs of diarrhea or discomfort after consuming cow’s milk, giving it occasionally shouldn’t do any harm. If providing milk as an occasional treat, choose higher-fat milk or cream, which contains less lactose than low-fat milk (100 grams of fresh cream contains 2.5 grams of lactose, compared to 5 grams in low-fat milk). There are also special lactose-free cat milk products available at most pet supply stores.
Cats don’t need milk in their diets. Although a small amount of preferably high-fat milk as an occasional treat is unlikely to cause most adult cats any serious harm, it should not be given as a regular dietary staple.
Kittens Should Not be Fed Cow’s Milk
Young kittens do have the lactase enzyme so that they can digest their mother’s milk, but cow’s milk is very different from cat’s milk. Its lactose levels are higher, its calcium-to-phosphorus ratio is different, and it doesn’t contain enough protein or fat to sustain a kitten. In addition to providing insufficient nutrients, cow’s milk may cause severe diarrhea in young kittens because it’s so different from the type of milk they’re supposed to consume. Diarrhea in kittens can quickly become life-threatening due to dehydration.
If caring for a young abandoned kitten, kitten milk replacer formulas, which contain the appropriate nutrients, can be obtained from veterinarians and pet supply stores. See How to Care for Young Orphaned Kittens for emergency kitten milk replacer recipes. Some of these recipes include dairy products with additional added nutrients. Because they contain cow’s milk, they should be viewed as temporary emergency formulas to be used only until the appropriate formula can be obtained from a veterinarian or pet supply store.
If caring for kittens that are in the process of weaning onto solid food, see What to Feed a Kitten.
Feeding Cats Goat’s Milk
Many people mistakenly believe that goat’s milk is lactose-free and therefore unlikely to provoke bad reactions in cats (or people) who are lactose-intolerant. Goat’s milk does contain lactose, though the quantity is lower (4.1 grams per 100 grams of milk, compared to 5.0 for low-fat cow’s milk or 4.8 for full-fat cow’s milk). Some cats are better able to tolerate goat’s milk than cow’s milk because of the slightly lower lactose content, but it can still cause diarrhea. Goat’s milk can be given as an occasional treat if a cat seems able to tolerate it, though it shouldn’t be fed on a daily basis.
- Cornell University College of Veterinary Medicine. (15 November 2006). “Ask Elizabeth.” Vet.Cornell.edu.
- Hartwell, S. (2008). “Human Foodstuffs Bad for Cats.” MessyBeast.com.
- Max’s House Animal Rescue. (n.d.). “Kittens.” MaxsHouse.com.
- Veterinary & Aquatic Services Department, Drs. Foster & Smith. (2010). “Feeding Dogs and Cats Milk May Cause Diarrhea.” PetEducation.com