Abnormalities of the estrous cycle

Veterinarians and dog breeders expect that all bitches will follow a typical estrous cycle of proestrus with serosanguinous vaginal discharge (nine days),estrus standing behavior (nine days) and diestrus (60 days). Breeders often assume that the bitch should be bred on the tenth and twelfth day of her estrous cycle. In reality proestrus can last up to 17 days, estrus can last up to 17 days and diestrus can last 56-58 days after ovulation. Beyond the typical (normal) estrous cycles a bitch may exhibit an anovulatory cycles, slow preovulatory progesterone rise, a cycle with an insufficient luteal phase, a split heat, persistent estrus or may fail to cycle ...