In male and female cats and dogs, neutering can keep pets from wandering and roaming. This reduces their chances of getting into fights and getting hit by cars. Although females do not roam as much as males, having female cats and dogs spayed helps prevent intact males from gathering around homes of female pets. Neutering male pets also helps prevent problems in the long run. Early neutering of male cats also will prevent development of urine marking behavior.
Veterinarians often prescribe spaying and castration as part of a treatment for some diseases.
Neutering also prevents the passing on of hereditary diseases. Having pets neutered also has benefits for pet owners. Besides preventing unwanted pregnancies, neutering can make some pets more friendly and keep them closer to home. Some people think that neutering a male dog will make him less protective of his home, but that just isn't true. Neutering male dogs may make them less aggressive in some situations, but should not effect their protective instincts toward their homes.