Nutty. I react to dog scratches like that, well like most people do, I don't think he and the dog have been in the same room at all today. She's been too busy trying to scare off the snow by barking at it
I've been coming up in similar weals since an allergic reaction to anti-biotics recently. Mine are smaller though, and itchy. When I scratch I get the weals. So maybe an allergic reaction? Or maybe he scratched himself post snow ,as skin can itch when warming up, but didn't register it as he was cold and numb, so scratched quite deeply?
ok read your post again, hadn't absorbed the "shoving it down collars" bit. I think the marks are the nails of the shover, <adjusts deerstalker, puffs pipe> not felt at the time due to the numbing effects of snow.
I have personally shoved snow down the back of several necks, and my arm tended to reach down as far as is humanly possible ,like a plunger, for maximum effect. <smugly convinced of the rightness of my theory>