
This has recently been mentioned in this thread.
[Link]http://www.champdogsforum.co.uk/cgi-bin/board/topic_show.pl?pid=593993;hlm=and;hl=The%20Pill#593993[/Link]
I would never give hormones to prevent seasons in a bitch I wanted to breed from. There is a high risk of a bitch developing Pyometra once you let her have seasons again, and it seems to be linked to cyctic ovaries too.