On Xmas day my 3 yr old staffy X cattle dog was walking around the house when all of a sudden her back legs looked like they stiffened up and they looked like they wouldn't go where she wanted them to (imagine stiff and wobbly but in a straight line) I stopped her from walking and when she walked again about 10 seconds later she returned to normal. This has only happened the once so far and I'm not sure what it is. Can anyone help? She didn't seem to notice it was happening and wasn't in pain at all..she is pretty active and does crazy jumps to her toy in the air.. Could it be a pinched nerve??