Spaying female dogs and cats and neutering male dogs and cats is considered the most effective and permanent method of birth control for these animals. In male animals, neutering involves the removal of the testicles, which eliminates the production of sperm and greatly reduces the animal's ability to impregnate a female. In female animals, spaying involves the removal of the ovaries and uterus, which eliminates the animal's ability to become pregnant. While no method of birth control is 100% effective, spaying and neutering have a very high success rate and greatly reduce the likelihood of unwanted pregnancies. Additionally, spaying and neutering can provide other health benefits for pets, such as reducing the risk of certain cancers and behavioral problems.