I don't know if oranges are dangerous for dogs but I hear that canned pumpkin helps with this... make sure you get one that has nothing on it -it has to be pure pumpkin.. You can find it in the cake mix isle at the grocery store..
Nummy Tum Tum is the one I hear about the most (found at pet stores) -
Nummy Tum Tum
Don't overdo it though.. I hear that it's not good to give them a lot... Good luck and keep us posted!