Although it is often assumed that cats must have milk, this is not necessary and beware, particularly with breeds of Oriental origins such as Siamese.
Such cats often lack the necessary enzyme to digest the milk sugar known as lactose. What then happens is that the lactose ferments in the kitten's intestinal tract, leading on to diarrhoea. It may therefore be safer to purchase specially formulated milk for cats, which contains very low levels of lactose, rather than giving them ordinary cows' milk.

Milk is not an essential part of a kitten's diet, because the nutrients in milk are present in adequate quantities in a complete kitten food. Water on the other hand is vital, and should be constantly available. The amount which a kitten drinks will be influenced not just by the weather, but also by its diet, with cats on dry diets drinking more water than those eating fresh or so-called "wet" food sold in cans and pouches.