for cats: it is generally considered safe for kittens as young as eight weeks old to be spayed or neutered. in animal shelters, surgery is often performed at this time so that kittens can be sterilized prior to adoption.
my kitty got hers done when she was 4 & 1/2 months.
Answer:
atleast 5 months of age or before. But I think that at any age u could get them neatured, except being too young.