Free, the 3rd in the series (start here if you like)
The Black Goats (Wine of the Gods Book 3) by Pam Uphoff
They were the last magic users in the world.
Seventeen witches and eight badly inbred mages. Nine wizards, eight of them transformed into large black goats.
Perhaps the gods should not have drunk so much
Definitely not PG13
http://www.amazon.com/dp/B0060E7KOY/
http://www.amazon.co.uk/dp/B0060E7KOY/
http://www.amazon.ca/dp/B0060E7KOY/