2. Reduce aggression in male dogs - not always the case, but can help in extremely aggressive males.
3. Reduce wandering behavior and sex drive (less leg humping!)
4. Reduce their need to "mark their territory."
5. Less unwanted pregnancies. There is already a population problem, of course due to overbreeding.
The main benefits of neutering in female dogs :
1. Eliminates the need to be concerned about uterine or ovarian cancer, and greatly reduces the likeliness of breast cancer, especially if your dog is neutered before her first heat.
2. No more strange male dogs showing up drooling at your doorstep when she comes into heat.
3. No more daipers! Spayed females will no longer "spot blood" during their heat!
4. No false pregnancies or infection of the uterus (pyometra) which can be life threatening.
5. Reduced chance of mammary, ovarian and uterine tumors
So if you have been putting off getting your pup an appointment with the vet, you may want to reconsider.