At least the implant is an option. I had some success with one of my worse chronic layers with Dr. David McCluggage, a holistic vet in Colorado. He works with patients from other states via phone consultation. At the time it was $75 for 45 minutes and he recommended a liquid holistic product he created called Sepia which calms the ovaries down. It was very inexpensive. It takes about 6 weeks to work but by the end of the 6 weeks it turned her right off. I was elated. I had asked him if it would wear off and he said no, but if for some reason it did to call the office and order some more. Well, she did start again so I called the office and they refused to ship the Sepia without another phone consultation with him which I couldn't afford. Here is the link to his practice if you're interested:
http://www.wellvet.com/about-dr-dave.html It's been years but as I recall I added it to her drinking water and it didn't put her off drinking it.
Cathy