Our vet recommends waiting to spay our female until she is 7 months. I would love to wait as much as I can but we have a 2 year old Presa Canario male who is in tact and I would love to avoid any possible issues. I would love to do it right before her first heat but no one can really tell when that is. Would it be safe to spay her at 6 months, just in case?