The ordinance applies to all 134 unincorporated communities in Los Angeles County, including La Crescenta, Bell said.
Cities within Los Angeles County, like Glendale and La Ca"ada Flintridge, have the latitude to accept county policy or not. Neither city has adopted the county policy.
Under the ordinance's requirements, dogs 4 months and older will be required to be spayed or neutered unless there is a medical reason why they should not be, or if they are law-enforcement, service or competition dogs, said Marcia Mayeda, director of County of Los Angeles Animal Care and Control.
All dog owners will also be required to implant microchips in their dog, for tracking, Mayeda said.
The microchips ? about the size of a grain of rice ? are implanted under the skin between a dog's shoulder blades. The chips assign a dog a unique identification number that will be listed in a national registry, she said. The number can be read by waving a scanner over a dog's neck.
"The reason for that is we are overwhelmed with these dogs [at the shelter], and many do not come in with any traceable form of ID," Mayeda said.
Dog owners and licensed breeders will also be limited in breeding ? female dogs 1 year and older will be allowed to have one litter a year, and will not be allowed to have more than five litters in their lifetime, Mayeda said.
"There is a two-prong reason for doing this, and one is public safety," Mayeda said.
Spay or neutering dogs reduces the aggression in dogs, and makes them less likely to roam, less likely to mate, less likely to bite people and less likely to get into dog fights, she said.
"The second thing is reducing the number of animals put to death in public shelters," she said, adding that at the county's animal control center, 18,800 dogs were put to death last year.