The urine of a neutered cat is also less smelly. Tomcats tend to roam long distances. This means they are often away from home, sometimes for days on end. Roaming puts these cats in danger, as they are more likely to be hit by a car, poisoned, or be hurt by dogs and people. Prevent injuries and disease.
Tomcats tend to get into catfights over females and territory.
This means they may get injured and are more likely to be infected with disease. By the way, this also means that it is virtually impossible to keep two or more unaltered male cats together.