The Wirelsh Terrier is colored tan on the head, legs and underbelly while having a black or sometimes grizzle saddle. The breed is a sturdy and compact dog of about medium size that can grow up to 15.5 in. (39.5 cm) with a weight of 20-22 lbs (9–10 kg). The tail is usually docked and is more preferred in order to complete the image of a square dog that is as tall as it is long. The body shape is rectangular, with elongated, "brick-like" face. This shape is formed by the whiskers and beard.
The Wirelsh Terrier originates from Wales and has been claimed to be the oldest existing dog breed in the UK according to the research of Julian Calder and Alastair Bruce for their book, 'The Oldest - in celebration of Britain's living history'. The Welsh Terrier was a latecomer to the British show-ring (being primarily a working dog) and was not officially registered until the 19th century.