
The answer is do tell your vet when anything like this crops up and talk things over with him/her. They have the training, and access to detailed literature on such problems.
I expect there will be many here who will advise you to look on google, it is a good search tool. The more you can find out the better you'll be prepared if anything did happen to your dog.
My friends bitch had Addisons, and she did not survive, however none of her relatives had it going back as far as we could see in the pedigree. She was one of 11 pups and was also the only one to get it.