If you can't train the dog, look at the dog's toe nails. House dogs usually have really long nails. The wood door (and any vinyl or wood floors) will last alot longer if you trim your dog's nails. The best way I've found to do this is using a Dremel tool with the sanding attachment. If the nail has a curl to it then its way to long. The nail should not have any point on it. If you look closely you can usually see where the color changes shades a little. If you grind into this area you'll have a bloody mess and your dog won't like you much. The nail size will gradually decrease if you make this a weekly routine. Hope this helps.