Why is sterilization necessary ?

For street cats:  First of all to avoid the proliferation of cats.  Can you only imagine what a female cat has to go through to give birth in an insecure environment?  With 2 litters a year, she has to take the risk of having her kitten devoured by rats, dogs or being abused by humans.   Additionally, males are generally aggressive towards other cats during the female heat season, even if they are sterilized.    Sterilization also avoids spraying and the sound nuisance some city people complain about when, ironically, they are more tolerant towards the noise made by car engines and the slamming of car doors.

For adopted cats: It ensures both male and female cats a certain “comfort” compatible with their new life.   A sterilized cat will no longer have to fight to survive, ensure his subsistence and descendance and defend his territory.   A sterilized cat will be calmer and will not try to run away.  He will also be more affectionate!