According to a new study that was done by researchers and according to a report made by the New York Post which was published on Jan. 5, dogs relieve themselves north-south, not east-west. This is because they are totally attuned to the Earth's magnetic field. The study that was done was done with 70 different dogs, 37 different breeds, watching them poop 7,000 times. They actually align themselves with Earth's magnetic field when doing their business.
No one knows why! It is all still a mystery and we will probably never know why they do this, but they really do. While the researchers were studying the dogs pooping while aligned to the magnetic field of the Earth, they also studied the magnetic field. They also found out that even one little change in the magnetic field can throw the dogs off easily. No one knows why this is either but it is.
When a dog needs to relieve himself by either pooping or peeing, they require a calm environment for them to do so by assuming the polar position.
Will we ever understand dogs totally? I don't think so but maybe one day we will understand them a little bit better than we do now.