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Updated: Jul 11, 2026

Rodent Estrous Cycle Monitoring Utilizing Vaginal Lavage: No Such Thing As a Normal Cycle
Published on: August 30, 2021
Unusual and abnormal canine estrous cycles
1Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Hungerford Hill Road, Ithaca, NY 14853, USA. vnm1@cornell.edu
Abstract:
Preovulatory serum progesterone concentrations are used to estimate the day of LH peak (day 0), not only to accurately time insemination and predict parturition, but to identify abnormal or unusual estrous cycles due to ovarian dysfunction. Early identification of these disorders is of therapeutic and economic importance. This review discusses anovulation, slow preovulatory progesterone rise, "split heat", insufficient luteal phase, and persistent estrus in the bitch. Some of these were temporary dysfunctions; with appropriate breeding management, pregnancy can be achieved. However, in other cases, these were signs of severe, permanent ovarian dysfunction associated with infertility, with potentially lethal sequelae.
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