I have been able to stop veileds from laying eggs but I can only seem to lower the clutch size in the panthers. Someone someday might figure out how to stop them.
There was a study done starting in 2007 with veileds that was started due to the reproductive issues and with the hope that there could be a birth control method found. There was a lot learned about the hormone levels but the study did not result in a birth control method. Hopefully someone will continue working on it!