Hayvanların gerek kızgınlık devresinde, gerekse bu devreden önce ve sonra görülen menstrüasyonla ilgili histolojik ve fonksiyonel olaylar, kızışma devresi, östrus
Period in the sexual cycle of female mammals, except the higher primates, during which they are in heat (ready to accept a male for mating). Some animals (e.g., dogs) have only one heat during a breeding season; others (e.g., ground squirrels) will come into heat repeatedly during the breeding season until impregnated. During estrus the female secretes pheromones that signal her receptivity to the males; her genital area may become swollen, and she may also give behavioral signals