As one who has used the Deslorelin implant for many ferrets, I can say that I much prefer it to Lupron Depot, and although more expensive initially, it lasts a lot longer. In the long run, it is cheaper, and also necessitates fewer vet visits. However, the 12-18 month window of effectiveness that you mention is incorrect. 12 months is the high end, and that is for a ferret that either does not have adrenal disease, or has early-stage adrenal disease. The more advanced the adrenal disease, the sooner you would need to re-implant with Deslorelin. 6-12 months is the realistic length of effectiveness. Also, if the ferret does have adrenal disease, using a melatonin implant in addition to the Deslorelin provides the best non-surgical treatment of the disease. Melatonin implants can be effective from 3-6 months, depending on the stage of the disease. I personally use melatonin implants for all of my ferrets, and if/when they actually develop adrenal disease, I then add a Deslorelin implant. Jeff Caring for Boomer, Zoomer, Gemini, Bella, Pinky, Simba, & Nala In memory of Luna, Neo, Sweet Sylvie, Baby Girl, Dozer, Morphy, Trinity, Sabrina, Minnie Mouse, Pop, Pip, Possum, Hunny, Mr. Parker, Misty, Frodo, Baggins [Posted in FML 7941]