How old does my dog need to be to be desexed (speyed/neutered/castrated)? By Matt Young Feb 25 2016 First of all a couple of definitions: Castration is the desexing of a male dog by removal of the testicles, sometimes this is referred to as neutering Spey is the desexing of a female dog or bitch when the ovaries and uterus are removed. Tags: dogcatdesexingspeycastrationage