Besides all the other good reasons to neuter your male cat -- such as avoiding feline overpopulation and reducing fighting and roaming -- another one stands out. Neutering often stops male cats from getting into the habit of spraying, which can start at the age of 6 months or earlier.
Why Cats Spray
A male kitten reaches puberty at about the age of 6 months; spraying is a way of marking territory and letting females know he's in the area. While most male cats stop spraying after neutering, you may be able to prevent spraying by neutering your cat before he reaches sexual maturity. Talk to your vet about neutering your kitten once he reaches a certain weight, generally about 3 pounds.