My vet said at least one heat cycle to make sure all the growth is complete. After that, the risk of mammary cancer goes up quite a bit from 8% to 25% and stays there. My understanding is the risk for mammary cancer is less than 1% if spayed before the first heat cycle. My dog went through one heat cycle, and then I waited until before I thought she might get her next one to make sure she was fully grown.
Last edited by chizelhead; 08/28/22.
