Stops The Bloody Discharge of a dog in heat. The discharge, which can stain rugs, furniture, etc., attracts male dogs. Reduces The Urge To Roam in search of a mate- which, in turn, reduces the risks of fights, injury, poisoning or death in traffic. Reduces Mounting of furniture, cushions, and people's legs by frustrated dogs.
Cats have fewer breast tumors, but when they do, they are nearly always malignant.
Spaying almost eliminates the risk. Neutering lowers the risk of this painful disorder. Both dogs and cats have reduced risk of prostate cancer if neutered, and no risk of testicular tumors.