Dogs preferred to excrete with the body being aligned along the North–South axis under calm magnetic field conditions. This directional behavior was abolished under unstable MF. The best predictor of the behavioral switch was the rate of change in declination, i.e., polar orientation of the magnetic field.
This is found in a paper published in 2013 the magazine “Frontiers in Zoology” Here’s a link to the article Canine-Magnetics
I have included a PDF file >> Click here>> Dogs are sensitive to small variations of the Earth’s magnetic field.