Cats

[GroovyLady]

How does neutering cats stop them fighting?

[naz_nomad]

Because there's not much point having a good scrap unless you can deliver a swift kick in the nads, is there?

[YvonneM]

NO the most evil cat on our road is a neutered Burmese he fights with all the other neutered cats

[drgnrdr]

maybe someone can give a long reason, but simply as I can it's the testosterone/hormones that drive them to fight for mates and the right to do so. But usually if a cat is properly socialized when young and the testorone is taken out of it, they grow up not fighting so much, just fighting to defend themselves when needed, not looking for a fight. Some say it's nature/nurture, if bred from aggressive parents this can cause your cat to be so. If a cat gets into the habits of marking and develops this way he will keep doing it even if the hormone is gone, habit is hard to break. But they say neutering helps calm them down a bit, but if you wait too long the percentage of it being helpful in behavior goes down. But the longer it goes also can give your cat undo health risk and heal time is longer with complications sometimes.
So "spaneuter" early...I advocate keeping them inside anyway, even tho it's not done as much in the UK.