DENVER (CBS) – A proposal to ban cat declawing passed in Denver’s city council Monday night.

The council unanimously approved a first reading of the ban, 11-0, last week.

Veterinarians call declawing a major and often painful surgery. The procedure is an amputation of a cat’s first knuckle.

The ban outlaws the procedure in Denver unless a surgery was medically necessary.

Vets say cats who are declawed are more likely to exhibit bad behaviors and eventually cause owners to give up on their pets.

A ban could potentially lower the number of cats in rescue shelters.

Most veterinarians already say they won’t perform a declaw surgery for an owner’s vanity. However, supporters of the ban say a regulation is needed.