Well it entirely depends how much you're willing to spend. There are these sort of mat things you can buy, that you sow your grass through. They're meant for really heavy traffic areas. I don't know how much it would cost to do your whole backyard, but I wouldn't imagine it'd be cheap... Would probably solve the problem though. Was discussed in this thread
boxerworld.com/forums/showthread.php?s=&threadid=36883&highlight=grass
boxerworld.com/forums/showthread.php?s=&threadid=36883&highlight=grass
