Abstract: A device and method for measuring the mouth of an animal are provided. The device includes a gripping handle and rod coupled to a first endpiece. The rod is threaded along at least part of its length. The device includes a second endpiece that includes a threaded hole. The second endpiece is rotatably threaded onto a threaded portion of the rod. The threads of the rod and threaded hole cause the second endpiece to move laterally along the threaded length of the rod when the second endpiece is rotated about the rod. By placing the rod adjacent to the mouth of an animal and rotating the second endpiece until the first and second endpieces are located adjacent to boundaries of dimension of the animal's mouth that is to be measured, the desired dimension of the animal's mouth can be determined from the distance between the first and second endpieces.