Are cats healthier when the drink water or milk?

It depends: if you have a female dog that has puppies the puppies will drink the breast milk from the mother but the mother still drinks water. if you have a puppy and not its mother either call the vet and buy special milk or just give it water.

For cats, I would make sure toilets that are not being used should be flushed at all times. for both kittens with or without their mother give them warm milk. Weaned kittens and adult cats should be given water, or formulated kitten milk. Cats of all ages should not drink cow's milk as it can make them sick.