My 6 month old boston terrier poops in her cage every time that we leave the house (not only does she poop, but she stomps on it and smears it all around the cage and on herself). It doesn't matter how we are gone, 30 minutes or 8 hrs! She never did this before - it just started last month when we left her and ou lab at my in-laws while we went on vaccation for 2 weeks. Ever since then she has pooped every time that we leave her. I called the vet and they said that it was most likely stress related to her not knowing if we will come home? I don't know if this is true or not? Any suggestions on what the problem could be or how to stop it?
Please help.

Dogs never explain why they do things. I don't trust anybody that insists they really know what is going on in those furry little heads. You often hear the term separation anxiously. It is only natural that a puppy resists its crate at first. What the puppy wants more than anything else is to be others, you, anyone else in the household, and any other pets. In our modern society, even if we are home, other things distract us from the attention an uncrated puppy must have. The only real solution is to crate the dog when you aren't around. In addition to not wanting to be left alone, she may be feeling she is a big girl now and challenging you for pack status. Whatever the reason, she has found an effective protest. It is hard to hide emotions from a dog, but the calmer you are when you find the mess, the better. Just matter of factly go about cleaning it up.

Having a good pack structure reduces such problems. The dogs see all the
People and dogs in the household as a pack with each having their own rank in
The pack and a top dog. Life is much easier if the 2 legged pack members
Outrank the 4 legged ones. You can learn to play the role of top dog by
Reading some books or going to a good obedience class. A good obedience class
Or book is about you being top dog, not about rewarding standard commands with
A treat. Start at http://www.dogsbestfriend.com/.

I am not sure how soon the obedience training will have effect. It may be a matter of outlasting her too. A wire rack in the bottom of the crate will reduce the mess in the mean time. They are available with the crates, but a piece of closely spaced wire closet shelving from a home supply place is cheaper. At least that way, the stools are quickly pushed below the rack before she makes too much of a mess of her self. In any reasonable weather, I haul a fouled plastic crate outside and hose it off. With a wire crate, you mostly need to clean up the tray.