I would talk to fence people in the area, and also a vet.

Not much is ''coyote proof''other than chain link buried in concrete and going up about 10' with a razor wire on top. The prison look isn't very attractive though. A plain chain link coupled with owner supervision will usually work to keep them intimidated enough though.

There are several websites dedicated to "predator proofing" animal enclosures such as chicken and rabbit hutches and dog kennels. Here's one I found: http://www.scwildliferescue.org/Predator_Proofing.html

Here's another:
http://www.dogster.com/lifestyle/protect-your-dog-predators-coyotes-birds-of-prey