When my dog had surgery, the cast needed to be covered and kept dry whenever she went outside. The vet gave me an IV bag and used tape to hold it in place. Kaylee has long legs, and the iv bag barely made it to the top of the cast. I crocheted a cuff attached to the bag, and included eyelets for a tie.
I’m not an experienced crocheter, so this is more of a recipe rather than a real pattern. Hopefully this will give you a start so you can make your own version of the cuff.
The cuff I made measures 3” from the top of the bag to the top of the cuff. The whole contraption measures 12 ½” from the floor to the top of the cuff. Good luck, and best wishes for your dog’s speedy recovery.