One idea you could try too depending on the size of your dog is place a baby gate in the doorway of your room or where the gliders are?
(If big dogs, might want to put up 2 baby gates, one over the other' it might be a little work taking a gate down to get past; but hopefully this will keep the dog out)
I can understand how frustrating it can be living with someone else's pet. I hope this idea helps!
A new sturdy cage is a good idea, lilsistar provided a really good link to cages that can take a harsh beating.