Investigations on endocrine responses in the bitch following hysterectomy

In most domestic species (e.g. cattle, sheep) prostaglandin F2α of endometrial origin is considered to be the active principle leading to luteolysis at the end of the estrous cycle; hence in these species hysterectomy leads to the formation of a persistent corpus luteum, the application of PgF2α induces luteolysis. Data for the bitch are conflicting; while exogenous application of PgF2α or analog acting compounds can lead to a decline in peripheral plasma progesterone levels [1], hysterectomy during the on-going cycle apparently does not lead to early luteal regression [2]. In order to obtain further information, a long-term study was designed of hysterectomized bitches and an equal number of control animals.