All in all, an altered pet is more pleasant to have around. There is always a slight risk involved in any surgery. However, the anesthetics used by veterinarians today are very safe. Many veterinarians also use heart and respiratory rate monitors. Even experienced breeders are fortunate if they break even on raising purebred litters.
Pets often have litters at inconvenient times and in unusual places.
The mother can also become very upset if not given the privacy she desires. These intrusions can cause the mother to have problems, such as unwillingness to care for her babies or injury to owners. Breeding two animals rarely results in offspring that are exactly like one of the parents. And, that's with purebreds. It's virtually impossible with mixed breeds.