Cerebellar abiotrophy in horses was originally thought to be a form of cerebellar hypoplasia (CH) and was described as such in older research literature. However, it was discovered that in horses, the die-off of purkinje cells began after the animal was born, rather than occurring "in utero." Cerebellar hypoplasia is distinctly different in that it is a condition from a lack of these cells being formed during the development of the cerebellum and is not progressive or degenerative. CH has been found in several species, including: cats, dogs, cows and lambs.