yeh cant beat a good jrt as they have never been bred to close just worker to worker, and who knows what they are bred from, you will seldom see a sick or mangey jr seem to be imune to most things.
Funny you should say that I said exact same thing to wife earlier today. I was taking cocker for walk she said watch where you take him as he spent few days in vets week or two ago with some mystery illness and I said I have never known one of my terriers be ill