Illustration of Jack Russell Terrier phenotypic variation. (Top) A tri-colour (brown, black, white) and smooth coat texture JRT. Notice the areas of white are not pure white as specks of black can be seen in the white on the hindquarter, forequarter, and main body. (Bottom) A black and white, broken coat texture JRT. Notice the overall amount of white present compared with the JRT pictured in the top. Minimal specks of black can be seen in the forequarter and the dog's left ear, but the white on the main body and hindquarter has little to no specks of colour. This dog has a broken coat texture; a combination of rough and smooth, with the rough texture on its nose/head and the majority of the rest of its coat is smooth. These dogs were not included in the dataset presented in this study and their images are included for illustrative purposes only.