It comes as no surprise to anyone that grooming has hygienic benefits. It helps eliminate parasites, keep the cat’s coat clean and smooth, cool the cat down through evaporation of saliva, and stimulate glands attached to hair roots that secrete substances to keep fur waterproofed. However, grooming can also have psychological benefits. A cat may groom to temporarily reduce conflict, frustration, or anxiety. Under these conditions, licking becomes what is called "displacement behavior." Displacement behavior can occur when an animal is motivated to perform two or more conflicting behaviors simultaneously. Unable to do so, a third behavior arises that is out of context with the situation. For example, during a social conflict a cat who feels threatened may be conflicted between running from his or her attacker and staying and fighting. Caught in a bind, the cat decides to groom instead! In these situations, grooming appears to calm and reassure the cat.
Over-grooming, in the form of excessive licking, biting, nibbling, chewing, or sucking the coat or skin, with no underlying medical cause, is typically indicative of stress. Common causes of feline stress are fear, lack of stimulation, isolation, new pet in the household, a move to a new household, separation anxiety and, in some cases, early weaning. Over-grooming becomes problematic when it results in self-inflicted injury (hair thinning, removal of complete tufts of hair, skin infections), a condition called “psychogenic alopecia.” This diagnosis is made when no underlying medical condition can be detected. In some cases, excessive grooming can start in response to a skin irritation (caused by fleas, allergies, infections), but this can escalate into a behavioral problem even though the condition has cleared. It is thought that the grooming behaviors become self-reinforcing by reducing anxiety. The grooming actions become repetitive, called “stereotypies,” that may come and go, depending on the cat’s current level of stress.