One thing I have read on other boards, and you can google for it as well, is to feed her cotton balls laced with cream. The cotton is said to bind up and collect the shards of glass and help make passing them easier. I believe the cream is only to make the cotton balls more palatable and easier to swallow themselves. It must be real cotton, not synthetic. I have read 5 cotton balls for a Lab sized dog.
I have not done this myself but it has come from sources I deem credible. If anyone else has more info on it please chip in.
Here is a link that says to do this but also says to check with your Vet. Even though you don't have a local E Vet, perhaps there is one in a neighbouring community you could call?