Answer:
When a female dog is spayed before their first heat cycle it reduces their chances of developing mammary cancer by 99%. Since a dog's normal heat or menstruation cycle begins at about 6 months, dogs should be spayed between 4 and 6 months. Male dogs can be neutered as early as eight weeks (two months) but some vets recommend that the owner wait until the dog is six months of age to be neutered. Talk to your vet to see what he or she recommends.