Plain yogurt? Generally fine in small amounts for most cats. Flavored yogurt? That's where you have to be careful — not because yogurt itself is the problem, but because of what's added to it.
The lactose situation
Most cats are at least somewhat lactose intolerant. They lose lactase (the enzyme that breaks down lactose) after kittenhood, which is why dairy products often cause digestive upset — loose stool, gas, vomiting. This is the same reason cheese in large amounts is a bad idea.
Yogurt is actually lower in lactose than most dairy because the fermentation process breaks much of it down. The live cultures in yogurt continue breaking down lactose even after manufacturing. This is why many lactose-intolerant cats handle plain yogurt better than milk or cream. A small spoonful occasionally is unlikely to cause problems for most cats — though it varies by cat.
The flavored yogurt problem
Flavored yogurts are a different matter. The issue isn't the dairy — it's the additives:
- Xylitol — an artificial sweetener increasingly common in "light" or low-sugar yogurts. It's toxic to cats (and dogs). Always check the label if you're considering giving any flavored yogurt.
- Artificial sweeteners — various others also not suitable for cats
- Fruit flavorings or actual fruit — some include grape or raisin flavoring, which is toxic to cats. Even non-toxic fruits add sugar without benefit.
- Chocolate — any chocolate-flavored yogurt is an absolute no
The safest approach is plain, unsweetened, unflavored yogurt — ideally with live active cultures. Read the ingredient list before giving anything to your cat. If it has more than a few ingredients, leave it.
In practice
A small lick of plain yogurt is unlikely to harm your cat. It's not going to provide any meaningful nutritional benefit either. If your cat is curious about it and you want to offer a tiny amount, that's fine. If they're not interested or it seems to upset their stomach, skip it.