noun, noun or participle which takes 'suru', intransitive verb
sexual excitement; estrus; rut; heat
Refers to the state of being in heat or sexually aroused, used for animals and sometimes for humans. The noun form is common; the する verb form is intransitive.
猫は春になると発情する。
Cats come into heat in the spring.
発情期の動
Animals in mating season can become aggressive.