Changes in housetraining habits

Question
We have a 3 1/2 year old Sheltie that was easily housetrained and up until about a month ago he virtually never had "accidents" in the house.  However, about 4 weeks ago we had to kennel him for two days due to a family emergency and since that time he has been pooping in the house at least once a day.  Our outdoor walking routine remains the same, but on many of the walks he seems to have lost his focus.  As an example, we went out for our regular 20-minute walk early this morning and he did not poop, but about an hour later he pooped in the kitchen.  I'm guessing he's "acting out" about something, but I have no idea what's going on in his head.

My question: how do I get him to go back to his old habits which were excellent?

Answer
Your sheltie's boarding adventure has obviously thrown his potty habits off, so you need a brief stint of housebreaking to get his head back on straight. Reinforce the praise outside when he eliminates, and when you know it is about time for him to poop and he doesn't (like on your walk), then crate him until you put him outside again. It is just a question of anticipating his actions and working with that using the crate and praise. He should come back around quickly.