Research overview: claw keratin structure, growth, and sheath shedding

A claw is a keratin sheath grown over the terminal bone of the toe, and this overview surveys its structure, continuous growth, and the way cats shed worn outer layers. Scratching strips off the old husk to reveal a sharp new tip beneath, which is why scratching posts accumulate claw casings. The keratin is layered for hardness and toughness, and growth from the nail bed replaces material lost to wear. Researchers study claw composition through material testing, histology, and comparison across species with different claw uses. Why it matters: understanding claw growth and maintenance explains feline scratching behaviour, informs the welfare debate around declawing, and clarifies how cats keep a perishable keratin tool functional across a lifetime of hunting, climbing, and territorial marking.