I know they make special bandanas, coats and collar covers for deaf and blind dogs. Although these are designed and sized for dogs (Great Danes mainly), they do have a "custom collar cover" size you could have made to go over her collar. http://www.thankfulpaws.com/deaf-bli...htm#deafCollar
If you are really concerned about it, I personally would get her an embroidered collar in a bright color that just says "I'm Deaf". Same concept as they are using for the dogs, but a permanent collar instead of a cover. Those are easy to read without actually having to catch her to look at her tag. Of course then you risk her catching it on something and it falling off since they're breakaway collars.