pooping in new places

Question
I have had my sheltie mix, Lucky, for 2 months now.  He is 7 years old.  He is a rescue dog and I don't know much about his training. He appeared to be well trained though.  He has NEVER pooped or peed in my house, not even at first.  Recently though he has pooped in 3 different friends/relatives houses.  He definitely did not need to go as he usually had just pooped sometimes less than an hour prior!  I have heard this may be a stress reaction from being in a new place.  What should I do about this?  I usually do not catch him in the act as he will go into the other room to do it.  It has been very upsetting for me since he seems to be so well trained and he will hold it for as long as he needs to at home.  There were other dogs in the home in two out of three cases, but he seems to get along with other dogs really well and one time there were no animals in the home at all.  Please advise, I appreciate any help at all!  Thanks!!!

Answer
Hello Helene,

Your dog is marking. Lucky feels the need to protect you by claiming new territory and
warning strangers that he controls the area.

If he doesn't already know, teach him to heel. Walk him at a heel daily, do not allow him
to sleep in your bed and do not coddle him. He needs to feel that you are a confident leader that
he doesn't need to protect. Go to my website at http://perfectdogtraining.com and read "Training Tips". This will give you more detail on being his leader.

Short term, keep Lucky on a leash and close to you when you visit friends.

Good Luck!

Sandy