There are many benefits for both you and your pet - Spayed females will avoid the risks of pregnancy and uterine infections, and will be far less likely to develop mammary cancer later in life. Neutered male cats do not spray your furniture, walls and plants to stake out their territories. Neutering also discourages male cats and dogs from roaming, decreasing the likelihood of fights, car accidents and disease. Neutering also reduces the tendency to be aggressive toward humans and other animals, and it lowers your pet's risk of developing prostate cancer and other diseases.