Salaam Alaikum

My husband and I have 2 x 6 month old kittens- one male and one female which we keep as indoor pets.

I have concerns about the male cat, particularly as my husband and I are about to Insha’Allah have a baby soon:

1- he can be rather aggressive and scratches;
2 –he will soon be spraying to mark his territory around the house;
3- it is likely that soon, he will be mature enough to mate and we will have kittens on our hands, which we will be unable to give proper care to.

We have considered having him rehomed, but he and his sister are the best of friends, so it would be such a shame to split them up and we know he will be cared for properly with us.

Our vet advises that we have him neutered in order to calm him down and prevent points 2 and 3 and advises that we should do so soon whilst he is still young. Is this haram?