"When a cat has parasites, cream, raw butter or even a little raw milk is good. Pasteurized milk is not nearly as good. When the parasite is gone or much reduced, most cats do not want dairy products, interestingly."
Source : http://www.drlwilson.com/ARTICLES/CATS.htm
Butter contains no carbohydrates, so it does not contain any lactose which is the sugar found in milk (and sugar is a carbohydrate).
Cream only contains 3% of lactose (carbs), which is 3 g of lactose in 100 g of cream :