Do cats make friends with other cats?

Yes, cats make friends with other cats. This applies to feral cat colonies and groups of domestic cats in households. Studies have concluded that within a colony of cats you will see clear friendships ("preferred associates" to use scientific language). "Preferred associates" are cats that are "found close to each other more often than they are to other conspecifics" (1). "Conspecific" means the same species of animal - i.e. another cat.

In their language, it appears that scientists are reluctant to attach the concept of friendship to cats. Although when two cats stay together throughout the day in a range of activities and places, as is the case in cat colonies, it would seem sensible to refer to these cats as friends.

Cat Friends - by Tim Pearce, Los Gatos

As expected, cats need to be familiar with each other to be more likely to remain close and allogroom. Allogrooming is mutual grooming - one cat grooms the other cat and vice versa.

When cats are related (e.g. brother/sister, cousins) there is an even greater likelihood that they will be close and allogroom.

Elisa, a regular contributor to this website has her own cat rescue and therefore multi-cat household and she will no doubt confirm the above.

Note: (1) The Welfare of Cats (Animal Welfare) by Irene Rochlitz.