Wikipedia
Keukegen
is a creature illustrated in Toriyama Sekien's Konjaku Hyakki Shūi. It resembles a small dog covered entirely in long hair. Its name is a pun - when written with different kanji (希有怪訝), keukegen means "an unusual thing which is rarely seen".
According to one report, the keukegen is a disease spirit which lives in damp, dark places and causes people in the house to get sick.