Prolonged proestrus in a bitch with X chromosomal monosomy (77,XO)

A stunted Miniature American Eskimo bitch that had signs of proestrus, which persisted for almost 8 months, had a 77,XO karyotype. Despite signs of proestrus, the ovaries were small and fibrous, and there was no evidence of ovarian follicle development or corpora lutea. Except for its juvenile appearance, the rest of the reproductive tract was grossly normal. Clinical signs in this bitch were similar to those in human beings with Turner's syndrome.