Can Cats Eat Dairy and Eggs?

Lactose intolerance in cats isn't an allergy or something that develops over time, it's a straightforward enzyme shortfall built into normal feline development. Nursing kittens produce plenty of lactase, the enzyme that breaks milk sugar down into digestible sugars, because milk is their entire diet. Once a kitten is weaned onto solid food, around 12 weeks old, the body has no more use for that enzyme and production drops off.

By adulthood, Cornell Feline Health Center puts the number at roughly 65% of cats with meaningfully reduced lactase activity, enough to qualify as lactose intolerant. In one of those cats, undigested lactose passes into the large intestine, where gut bacteria ferment it, producing gas, and where it also pulls water into the bowel by osmosis, the same basic mechanism behind most diarrhea. That combination is why a saucer of milk so reliably produces loose stool within about 8 to 12 hours, not immediately and not days later.

It isn't dangerous the way onion or chocolate is, just a predictable, avoidable stomach upset. Eggs run on a different mechanism entirely, and cooked, they're a genuinely better story. Egg is a complete, highly digestible protein with an amino acid profile well suited to a cat's biology, closer to what a cat is built to eat than dairy is.

The real risk with eggs isn't a built-in digestive limitation, it's specific to raw egg: bacterial contamination, salmonella in particular, and a protein in raw egg white called avidin, which binds the B vitamin biotin and blocks its absorption. Cooking neutralizes both problems at once, heat kills the bacteria and denatures the avidin protein, so a properly cooked egg carries neither risk. That's the split this whole category comes down to: dairy is a mixed bag because of how a normal adult cat's gut works, eggs are fine specifically because they're cooked.

Treat plain cooked egg, scrambled or hard-boiled with nothing added, no salt, butter or seasoning, as a legitimate small addition rather than an occasional novelty. A tablespoon or two of chopped cooked egg a couple of times a week is reasonable for an average adult cat, well within the roughly 10% of daily calories that treats and extras should stay under; use our calorie calculator to check where that lands for a specific cat's weight, and see our eggs guide for more on eggs specifically.

Egg yolk carries more fat and calories than the white, so it should count toward that same treat budget, not sit on top of a full egg serving. Dairy deserves a more cautious default. Milk and cream carry the most lactose per serving and cause the most predictable upset, so they're worth skipping for any cat with unknown tolerance, and worth dropping entirely once a cat has reacted to either.

Hard, aged cheeses like cheddar or parmesan are a different case: most of the lactose in milk is removed with the whey during cheesemaking, so these cheeses carry only a trace of it, which is why some cats tolerate a pea-sized cube where they couldn't tolerate milk; see our cheese guide for the full picture. Plain yogurt sits in a similar middle ground, since its live cultures consume some lactose during fermentation, so a small spoonful is tolerated by some cats that react to milk.

Cottage cheese and soft cheeses are fresher and less fermented, so they keep more of their original lactose and behave closer to milk than to hard cheese. None of this is a reason to build dairy into a routine: even a well-tolerated cheese or yogurt is best kept to an occasional, teaspoon-scale taste, not a daily habit, since the fat also adds calories a cat's diet doesn't need on top of a complete food.

When trying any dairy or egg item for the first time, start with a genuinely small amount, a pea-sized piece of cooked egg or a half-teaspoon of plain yogurt or hard cheese, not a full serving, and offer only one new item at a time. Introducing several new foods together makes it impossible to tell which one caused a problem if a cat's stomach reacts.

After that first taste, watch the next 24 hours rather than just the first few minutes: lactose-related diarrhea from dairy typically shows up within 8 to 12 hours, not immediately, so a cat that seems fine right after eating can still develop loose stool later the same day. If nothing unusual shows up, small, occasional amounts along the lines described above are reasonable going forward.

If loose stool, gas or vomiting does appear, that's a reasonable item to drop from that cat's diet rather than testing it again to see if the first reaction was a fluke, since lactase levels don't recover with repeated exposure. The same small-amount-first approach is worth applying to a new cheese, milk or yogurt brand too, since fat content and any added ingredients can vary even when the base food looks the same.