You might look at the UC-Davis website as they were doing research on dwarfism. I do not remember it being breed specific, so not sure if that will help you.
Julia
No, but I'd imagine there are several other possible causes just like in humans. Problems with growth hormone production. If you can't find anything on dogs, look at different causes for humans and see if that correspond with dogs.
If you are on RTF, do a search on dwarfism. It's been discussed a few times w/ and w/o relationship to RD. That was where I found that link. Good luck. Anne