Grooming Another Cat (Allogrooming)

Cats that live together and get along will groom one another, almost always around the head and neck — precisely the areas a cat cannot reach with its own tongue. This is allogrooming, and it is one of the clearest signals that two cats regard themselves as belonging to the same social group.

Part of its function is practical. Mutual grooming keeps hard-to-reach areas clean and helps with parasites. But the larger part is social. Cats identify group members largely by scent, and licking mixes the participants' odours into a shared 'colony smell' that marks them as familiar and safe. Cats separated for a while — a trip to the vet, for instance — often groom intensively on reunion, restoring a scent profile that a clinic visit disrupted. This is also why a returning cat is sometimes met with hostility until it smells right again.

There is a subtler layer too. Studies of colony cats have found that grooming is not evenly distributed: higher-ranking cats tend to groom lower-ranking ones more often than the reverse, and grooming bouts sometimes follow moments of tension. One leading interpretation is that allogrooming redirects mild aggression into a socially acceptable act, defusing conflict without a fight.

That helps explain the common sequence where a friendly grooming session turns abruptly into a wrestling match. Usually this is play or an ordinary shift in mood, and it ends as quickly as it started. Persistent one-sided grooming that leaves a bald patch on the recipient is a different matter, as is grooming that regularly escalates into genuine fighting.

For owners, the appearance of mutual grooming between cats — particularly newly introduced ones — is one of the best signs that an introduction has succeeded.