It could, but all dogs are different. I've done a couple of dogs at 4, one at 8. Nothing really changed with them. I was having a slight problem with peeing (too many intact boys in the house claiming stuff out of my sight). The 2 I fixed never marked in the house again. The one I left intact marks more, but that could have to do with having 2 intact girls in the house now. It is NICE not having to worry about their testicles anymore. We can go to parks, stores etc.