Grooming intensity and/or duration and/ or frequency may vary from the norm in two directions (over-grooming and under-grooming).

Over-grooming

Grooming to the point where hair loss is seen may occur in cats for numerous reasons, both medical and behavioural (Bradshaw, 1992). Patterns of alopecia (hair loss) may also vary although the most commonly seen pattern is hair loss over the caudal half of the body with a bilaterally symmetrical pattern. In some cases grooming occurs so intensively that skin lesions may be caused. As well as changes in intensity, duration and frequency of grooming leading to hair loss, an increase in nibbling or biting action when grooming may give rise to alopecia.

The following are pictures taken of a cat with severe hair loss through over-grooming.

Under-grooming

The most common reason for a cat grooming itself less than normal is illness or pain, for example that caused by arthritis in elderly cats, although certain states of chronic stress may give rise to reduced grooming (Beaver, 1992). A cat that is under-grooming usually presents with a coat that is of uneven quality and looks unkempt. Hairs may give the impression of clumping together and an excessive amount of loose, dead hair may be seen within the coat and/or lying on the surface of the coat as it is not being removed through the normal grooming process.