Bonnacon

Bonnacon (bonnacon, bonasus, bonacho) is a legendary creature from medieval bestiaries. The word comes from the Greek βόνᾱσος (bonasos), which means "bison".

He is described as a bull with horns bent inwards and a horse's mane. The fur is reddish-brown or black. 

Since his horns were useless for self-defense, Bonnacon was said to spew large amounts of caustic feces from his anus into his pursuers, burning them and thereby ensuring his escape.