I used PG600 with one of my girls that only cycles every 10-11 months. I followed Revival's recommended protocol - sunshine, doubling up on vitamins for the few weeks preceding the injections. I gave her the injection as directed on the appropriate day - apparently the injection is VERY painful, as she cried out and it took 2 people to hold her to complete the injection. She responded after only 1 injection and was in heat within 1 week. She ovulated 9 days after her first day in heat (which is a little fast for her by about 3-4 days) I bred her 2 days after ovulation. Everything seemed to happen slightly ahead of what was "normal" for her. I did her progesterone testing, and planned to breed her naturally. Well, the stud was super interested, but she would have NOTHING to do with him, was not flagging at all either - but the numbers were perfect. We tried again the next day, and ended up doing a side-by-side AI. Kept my fingers crossed that everything worked - but ultrasound showed no puppies - VERY disappointed to say the least.