I don't know if Sparkle actually suckled, but she was always at her own nipple - just ONE of them - for the first 4 months she lived with me. It was always red and sore-looking. Not knowing what was going on, I took her in to the vet who explained sometimes they will try to suckle on themselves. And said she would grow out of it, which she did. There really wasn't anything we could do about the sore nipple, just that having it sore would stop her doing that.