Settling Down?

First I would like to thank Linda for her responses to issues I posted early in our JRT ownership. I agree with and support the need for training and consistency with these great dogs. If not for your help and suggestions early on in our ownership, we would not have the best dog in world, Scooter, with us today (okay, I'm a little biased). Keep up the great work!

Now my issue. Scooter has went from being very active to being, more or less, what seems like out of shape. He use to run a couple miles with my wife and still have plenty of energy to chase the ball or me, for as long as we let him. Now, he can't run two blocks without sitting down and sometime not wanting to continue after a short break. He will come in from a short walk, drink a little, and lay down like he just ran a marathon...panting heavily etc. for atleast 5-10 minutes. While this is probably a dream come true for most owners, with Scooter being just a year old it is not what I expect, nor do I think it is normal.

Nothing has changed. His diet is healthy, he eats...he is not over weight. He is nuetered. The only thing different... he did spend two weeks with a relative who had dogs. They had a great time and Scooter adjusted fine when we brought him home.

We are planning on taking him to the vet, but I wanted to run this by the group first. We are just a 'little' concerned...if this is normal, then great! However we don't think this is normal behavior so any help would be appreciated. Sorry for the long post!