The series of bodily changes that occur in the female of most mammals from one period of estrus to another. The estrous cycle usually takes place during a specific period known as the breeding season, which ensures that the young are born at a time when the chance of survival is greatest.
ear-to-ear. It's about smiling. Ear-to-ear smile or grin is when you have a very broad and generous smile. Such a smile when each corner of your mouth is by each of your ears. Explain to me why you don't have an ear-to-ear grin right now.
Ears down can also mean friendliness. If she's looking at you, with ears back, wagging tail and lip licking, then it should mean that she's happy to see you. If she's afraid of you, she would avoid eye contact and even go away, and even with tails between her legs instead.