Page "Claw" Paragraph 16

Every so often, the growth of claws stops and restarts, as does hair.

In hair, this results in the hair falling out and being replaced by a new one.

In claws, this results in an abscission layer, and the old segment breaks off.

This process takes several months for human thumbnails.

Cats are often seen working old unguis layers off on wood or on boards made for the purpose.

Ungulates ' hooves wear or self-trim by ground contact.

Domesticated equids ( horses, donkeys and mules ) usually need regular trimming by a farrier, as a consequence of reduced activity on hard ground.