I wonder if lifting the leg is a learned behaviour. Vegas is 2 now but up until about a year or so he would only squat. Then we were babysitting a friends male dog. We were in the back yard and the older dog lifted his leg on a tree. Vegas was watching him, them did it himself in another area of the back yard. So it wasn't like he was marking his territory over the older dog, it looked like he learned it. Ever since he lifts his leg, although he still squats sometimes when he is lazy. Does anyone think this is a learned behaviour or just a coincidence?