Answer: Yes, they do. Normal hairs undergo a cycle of growth, unlike the claws which grow continuously. Firstly, there is period when the hair grows by the multiplication of cells at the bottom of the hair follicle deep in the skin; this phase is called anagen. This is followed by a period when the growth stops and the hair is retained in the follicle; this phase is called telogen. These non-growing hairs, called ‘club’ hairs, are less firmly anchored then the growing hairs and consequently are more easily removed. Removal may be grooming or simply by fraction from setting or laying. Eventually the cells which the hair begin to multiply again and a new hairs is formed. This new hair growth up the follicle; along-side the old club hair if this is still present, though as the new hair emerges at the surface the old hair becomes detached and is shed.
In the cat, as in the dog and man the growth of the hairs is not synchronized, i.e. they are not all at the same stage at the same time. Adjacent hair cab be at any stage in the growth cycle-the so-called mosaic pattern of the growth. However, in the cat the greatest activity (i.e. the most shedding of old hairs and growth of the new ones) occurs in the late spring when the hours of daylight markedly increase. The periodicity of light has more influence then the environmental temperature. The under hairs (secondly hair) often undergo a period of subsidiary growth activity in the late autumn (fall). Growth activity is minimal during the winter months.
The rate which hairs grow in the cat averages one hundredth of an inch (0.25 to 0.3 mm) per day, and is also least in the winter and greatest in the late spring. The sex of the cat and whether it has been neutered have a little effect on either the growth cycle or the growth tare. However, in generalized disease or ill health the total number of hairs in the resting phase increases so that increased shedding of the hair can be sign of illness. Also, in sane hormonal (endocrine) disorders many hairs enter the resting stage at the same time and are therefore shed simultaneously. Severe damage to hairs, for example by ringworm, may cause them to break off, leaving a stubble.
