If you purchased the horse using community funds (e.g. typically monies from a joint bank account), then the horse is community property. Getting a Quit Claim Deed fro the horse from your wife will not change that result because a Quit Claim Deed only works for real estate. If you wanted to make the horse an asset of your separate estate, then your wife should give you a gift letter in which she gives you her community property ownership interest in the horse.