Hay miles de gatitos sin hogar porque muchos dueños de mascotas no esterilizan a sus gatos.There are thousands of homeless kittens because many pet owners do not sterilise their cats.
Si hubieras esterilizado a tu perro cuando era un cachorro, no sería tan agresivo ahora.If you had neutered your dog when it was a puppy, it wouldn't be so aggressive now.
Queremos esterilizar a nuestra perra porque no podemos permitirnos tener cachorros.We want to spay our female dog, because we cannot afford to have puppies.