It's already law that your pooch must be snipped, but starting tomorrow it is enforceable. If you didn't know about this, that's because "though Animal Services is charged with enforcing the mandatory spay-and-neuter law, it does not intend to do so," according to City Controller Laura Chick's scathing audit released in the summer. The purpose of the law is help control pet population growth. In theory, the less the little buggers are born and in turn not adopted, the less Animal Service shelters will have to practice euthanasia in overcrowded shelters. Fines start in the triple digits.