You know when dogs piss against trees, does it damage them at all? In any way? I suppose it must. Anyone got any concrete evidence to support this though?

Dogs are silly. Sometimes they use lamposts as well, and the wee sprays both sides of the post, not just on the post itself!!!

Dog weeing is funny. Once, when I was younger at my old house, I went outside into the back garden for a wee (there was logic, I'm not just a dirty scrote - my mother was asleep upstairs and I didn't want to wake her, and I was also waiting patiently for the 15 minute Freeview on the Adult Channel) I'd stupidly left the back door open, and my dog came out and weed on my leg while I was taking a wee. It was highly unpleasant, and then I ended up waking my mum up anyway by running the shower at 12:01am. I also missed the freeview as a result. A bad day all round, really.