Anestrus and Diestrus

Anestrus noun - Applies to nonhuman mammals: a state or interval of sexual inactivity between two periods of estrus.

Diestrus and anestrus are semantically related. In some cases you can replace term "Diestrus" with "Anestrus", this nouns are similar.

Diestrus noun - (of animals having several estrous cycles in one breeding season) a state or interval of sexual inactivity or quiescence between periods of activity.

Anestrus and diestrus are semantically related. You can use "Anestrus" instead a noun "Diestrus".