The benefits of spaying a male are so significant, that it is possible to say that unaltered male cats cannot make good house pets. If you want to keep a male cat as a pet you simply must neuter him. Neutering a male cat before he reaches sexual maturity, almost always prevents this behavior pattern from emerging. If a tomcat had already taken to spraying, neutering is still likely to stop or at least significantly reduce the habit. 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.