http://news.discovery.com/animals/pets/dogs-have-a-butt-compass-poop-facing-ns-pole-140102.htm "Its all starting to make sense. For years I wondered why my dog spins in a circle before depositing her daily double. But now I think I have a clue as to why. Scientists at the Czech University of Life Sciences in Prague have found that, like other animals, dogs are sensitive to Earths magnetism. Dogs prefer to do their duty with their bodies aligned along the north-south axis, particularly under calm magnetic field conditions, report Hynek Burda, et al. in a study published in the Frontiers of Zoology. The field can fluctuate and I cant help but wonder if its on those unstable days that my dog circles round and round like a housefly on a windowsill. Animals Gone Wild On Spring Break: Photos The scientists came to their conclusion after measuring the direction of the body axes of 70 dogs, representing 37 different breeds, as they were making a deposit the dogs, not the scientists. The researchers observed both number ones and number twos over a two-year period. After sorting the data according to the geomagnetic conditions, among other technical variables, the team concluded that dogs were predictably sensitive to Earth magnetism and showed sensitivity to changes in polarity, rather than intensity of the magnetic field. Next time your dog poops, take note of the direction and report back."