thanks!!~

Your cats need to be almost full grown before spaying or neutering.
That said, even though the cat may not be completely grown, 7 months is
optimal for females, 6 months for males.  They can be altered before
this, but if the male is of persian descent or has a lot of persian
blood, the cat needs to be 18 months old before neutering.  They have a
condition where one of the testicles drops late, so even neutered for
the one testicle, they can breed.

Both can be spayed/neutered as early as 5 months.  Just expect the cats
to be fatter, less active and smaller-boned by being altered that
early. Extra play can help with the weight issue.

Morgen
http://www.for-the-love-of-cats.com/behaviors