sometimes you could be feeding the dog a food 2 high in protein especially if its a young pup to cure it change the food and wrap the dogs feet like it is in a cast. You can put a splint on the front of the leg and the back of leg to put it in the proper position. THen wrap it with the self adhesive wrap ( you can get it at a pet supply store, looks like an ace bandage.) Start the wrap about at the middle of the paws so only the toes stick out then go up to the elbow. Leave it on for about 7 - 10 days and it will straighten right up.
This is depending on if it is a young puppy and if you caught it on time. '
Good luck hope I have been helpful to you.