The Thai Ridgeback is a muscular, medium-sized pariah-type dog with a wedge-shaped head, triangular-shaped prick ears, and a very short, smooth coat. It has a pronounced ridge on its back formed by hair growing in the opposite direction that extends from behind the withers to the hips. Puppies are occasionally born ridgeless. Thai Ridgebacks have a muscular and streamlined body, making them extremely agile. The tail is carried upward called a sickle or sword tail. Its forehead wrinkles with enormous expression. Like many eastern breeds, the Thai Ridgeback has retained a ‘scissor jaw’ where upper and lower teeth interlock when the jaw bones clamp down. The tongue can be black or have black marks. Eyes are almond-shaped and brown but may be amber in blue dogs. The ears are set low and point slightly outward. The ears stand up progressively during the puppy growth period; they are not cropped. The back is straight and level. The coat is short, hard, and straight. Due to the length and density of the coat shedding is minimal, occurring once or twice yearly. Because this breed does not have an undercoat the hair does not usually bother people allergic to other breeds of dogs. Coat must be solid colors of blue, black, red or fawn with a black mask being acceptable on reds. However, brindle and white are also found but are not acceptable colors. For international show and competition, shoulder height should be 22-24 inches (56–61 cm) in males and 20-22 inches (51–56 cm) in females. The weight averages 35–55 lbs in females and 40-60 lbs in males.