To clean these places, cats lick their paws and then rub them over the face and head. If frustrated by a particularly rough, sticky or dirty patch on its coat, a cat may resort to using its teeth to tear or bite off the offensive material, along with the hairs. As a consequence of all this grooming, felines ingest a considerable amount of dead hair, which they occasionally vomit as hairballs. Longhair domestic breeds are prone to impaction of hair in the intestinal tract and may need regular doses of a hairball remedy to avoid serious problems. Frequent grooming of both longhair and shorthair cats by their owners helps to prevent problems by removing loose hair before it is swallowed.
Grooming also regulates body temperature.
In warm weather, the saliva acts as a coolant that can reduce a cat's body heat by as much as one-third. In lower temperatures, the rake-like tongue aligns the hairs of the coat so that they retain heat and keep out the cold. Depositing saliva on the coat has yet another interesting purpose. When cats scent themselves with their own saliva, it may relieve anxiety, offering a source of reassurance at tense moments. Cats appear to dispel fear, nervousness and pain by seemingly inappropriate or frantic grooming, much like human displacement behaviors such as nail biting or other nervous habits.