Flexibility and stretching exercises for dogs are used to improve joint motion and alleviate limb pain. However, there is a lack of information in the effectiveness of these canine exercises when performed by dog owners and caregivers. Current solutions for measuring range of motion are not designed to be worn by dogs. In order to evaluate the position of a joint at any given time, the user, the human assisting the dog in the exercises, must hold a digital or analog device while performing the exercise without real-time feedback associated with the dog's breed or joint exercised. We propose WOOFlex: a wearable that assists in canine flexibility exercises that (1) is attached to the dog's limbs so as to not interfere with the exercise, (2) includes IMU sensors to measure the joint angle, and a web application to (1) provide real-time visual and audio feedback for assisting the user in not exceeding safe joint angle ranges, and (2) to store exercise session data to monitor the flexibility progress.