Mayor Antonio Villaraigosa signed one of the country's most stringent pet sterilization laws yesterday, requiring dog and cat owners to spay/neuter their pets or face hefty fines. What does this mean for you and fido or fluffy? It means that you must have them spayed or neuteured by the time they reach four months of age. All dogs? All cats? Pretty much. The only animals exempted from the new law are those that compete in......