Hair follicle cycle and shedding in male beagle dogs.

Skin biopsy samples were collected from the thoracolumbar region of 9 male Beagle dogs ranging in age from 2 weeks to 32 months. The highest percentages of anagen hair follicles were present in samples collected during the winter and the summer seasons, and highest percentages of telogen hair follicles were present in samples collected during the fall and the spring seasons. Catagen, never exceeding 7% of the follicles, was found during a brief transitory stage. Peak shedding of hairs combed from the coats of dogs occurred in the spring and fall--these peaks appearing simultaneously with peak percentages of hair follicles in the telogen phase. Dogs younger than 1 year of age had 10% fewer follicles in the telogen stage than did older dogs. In dogs 2 weeks of age, 12 to 16% of the hair follicles were in the telogen stage.