Neutering eliminates the risk of testicular cancer and reduces the risk of prostate disease. When pets are spayed or neutered, their tendencies to roam or fight are greatly lessened. This prevents the pets from getting lost, stolen, hit by cars or contracting a disease. Cats that fight can contract a serious disease called feline leukemia. This disease, which affects the bone marrow and breaks down the immune system of the cat, can be passed from feline to feline through saliva or blood.
Cats also run the risk of contracting feline immune deficiency virus when they fight.
Spaying or neutering dogs can help keep them under control. Dogs that have not been spayed or neutered are more likely to run away from home. While running loose, they have a chance of being hit by a car, getting lost or taken to the animal shelter. I would advise pet owners to have their pets spayed or neutered. Usually the day after surgery, most pets are bouncing around as if nothing ever happened.