anestrus

reproductive cycle

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June 18, 2026

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Anestrus is the period of sexual quiescence, or inactivity, between periods of sexual activity in cyclically breeding mammals. This is in contrast to estrus, which is the period when a female mammal is receptive to mating. During estrus, the uterine lining thickens in preparation for potential pregnancy, and the female may exhibit behavioral signals indicating readiness to mate. Some animals are monestrous, having only one estrus period per breeding season, while others are polyestrous and will cycle repeatedly if not impregnated. Males can detect females in heat through pheromones. Anestrus, therefore, represents the time outside of this fertile window.12

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dog
Reproductive cycle
She then enters anestrus, which is the time frame between the end of the last cycle and the beginning of the next proestrus.
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She then enters anestrus, which is the time frame between the end of the last cycle and the beginning of the next proestrus.
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mammal
Estrus and other cycles
Metestrus may be followed by anestrus, a nonreproductive period characterized by quiescence or involution of the reproductive tract. On the other hand, anestrus may be followed by a brief quiescent period (diestrus) and another preparatory proestrus phase. Mammals that breed only once a year are termed monestrous and exhibit a…
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Metestrus may be followed by anestrus, a nonreproductive period characterized by quiescence or involution of the reproductive tract. On the other hand, anestrus may be followed by a brief quiescent period (diestrus) and another preparatory proestrus phase. Mammals that breed only once a year are termed monestrous and exhibit a…
Read More