Makes me wonder

This is Benji.  Benji is Bob and Grandma's dog. 

Benji spends a good part of his day perched on the couch looking at the world outside.  Whenever you drive to grandma's and pull up into the driveway, you can bet that Benji will be in the window- waiting.

He will run from one window to the other, to the huge sliding glass door in the back barking the whole way letting any and everyone know that he sees something.

It makes me wonder why a dog who seems to be obsessed with knowing what is happening outside pees and poops inside the house.  Why wouldn't he want to be outside?  I will never understand that dog.