Which of the following is NOT a stage in the bitch's estrous cycle?

• A. Anagenesis
• B. Anestrus
• C. Proestrus
• D. Diestrus

Answer: (A)

The stages of the bitch’s estrous cycle are proestrus, estrus, diestrus, and anestrus. Proestrus is when the vulva swells and there’s vaginal bleeding as estrogen rises, but the female isn’t yet receptive to mating. Estrus is the heat period when she is receptive to a mate; ovulation may occur around this time. Diestrus follows ovulation and is the luteal phase with progesterone activity, whether or not pregnancy results. Anestrus is a period of reproductive quiet between cycles.

Anagenesis, on the other hand, is not a stage of the estrous cycle. It’s a term from other biological growth contexts and does not describe a phase of the bitch’s reproductive cycle. So the option that doesn’t belong is the one referring to that term.