I think that the best way to know the ingredients of dog treats is to make them yourself. I know this is a little time-consuming and honestly a bit of a pain, but I think it's really the only way. Even if they list the ingredients, is it really that reliable? Sorry I can't help more...
Lots of the treats I buy have ingredients listed. In fact I'm a bit of a nerd, as every treat I buy I have to read the ingredients extensively before buying. ^^
However I have noticed that treat ingredient lists in general are very short....is there really not that much in them?
Which treats are you trying to buy that do not have ingredients listed?