In frontier areas, when livestock roamed without fences, farmers often had their own peculiar notch they used to identify their hogs or cattle. Records of these notches may be found at the local courthouse, recorded with other public records. In areas where branding livestock was a common practice, one may find records of brands. At the very least the image makes for a nice illustration.
In Fleming County, Kentucky, in the 1810s, a neighbor stole a hog belonging to one of my ancestors. It was taken to a neighbor’s home where it was butchered and the head was left in the barn. The identification of the hog was done because it had my ancestor’s notch in the ear.