It is your duty as a responsible dog/cat owner to spay/neuter your pets, both the purebred and non-pedigree.
Castration is the only humane and fully effective method of preventing animal homelessness. It is also the only 100% effective and safest method of contraception. Every single year, several million homeless animals die in animal shelters. By spaying/neutering your pet, you not only give it a much longer and happier life, but above all you help to reduce overpopulation and the magnitude of homelessness.