cats should not drink milk, it's bad for them. A different practice sentence would be better.
The vet and the internet. Cats lack lactase, the enzyme needed to digest milk sugars. They are lactose intolerant just like all adult mammals around the world except a chunk of white humans.
Cats like fat dairy such as cream but non-fat dairy such as milk is bad for them.
This is only partly true - much like another popular rumor about the 10%-capability of brain usage or the one that eskimos have 100's of words for snow, etc. The lactic enzymes prevents undesired "side effects" when consuming milk, but they are not an "antidote" against "milk-poisoning". Many animals (some better than others) can digest milk, just not as fast as it could have been done with enzymes like lactase. I've grown up in a village and have seen adult cats drinking a little milk and eating bread leavened in milk without having any visible reactions against it. Besides, Caucasian people are not the only lactose-tolerant human race - there are Saharo-Nilotic pastoral people who have also developed genes that allow them to consume milk without "side effects".
I'm going with what my vets tell me. A little milk might not be a problem for the few cats you knew. People thinking that cats drink milk for thirst is a problem. Domestic cats drink water.
I don't really care for cats but this is very important to know if you have cats
Can drikker be used for both 'is drinking' and 'drinks'?