Greetings Steph and MM You are likely to get a myriad of answers to your question! What breed are you considering? What do you plan to do with the animal? Other dogs in your household? A member recently posted an article on the front page about the results of a recent study at Colorado State University suggesting that early neutering may be a risk factor for developing excessive tibial plateau angle (TPA) in large-breed dogs with cranial cruciate ligament disease. Here is some more info...this article has been referenced in the past: http://www.caninesports.com/SpayNeuter.html Good luck.