Hi Sandy,
I'm sorry! I didn't mean to imply that you shouldn't have given DJ up. Definitely have to look out for the well-being of your first dog, and I can see how a rambunctious and good-sized pup could be too much for an older dog. I would have made the same choice.
I guess the distemper shots can only do so much if the dog is getting such a huge dose. Yikes! That's good to know.
Best regards, Michelle in Nevada