There may not be etiquette, but there’s certainly equestriette.

I’ll see myself out now…

From what I know, female animals “show” when they’re available. This can be through pheromones or some sort of behavior. But if the animal kingdom equivalent of the basement dweller “nice guy” comes along, they can get away relatively easily.

Caveat: This stipulates that the male doesn’t have the ability to grab.

Source: I loosely remember a natural geographic documentary about some deer-like creature in sub-saharan Africa. I would think horses are similar.

Also, the word you’re looking for is “mare”. Source: Grew up on a farm. Hick4lyf!

No etiquette. Lots of ravaging to the point of potential injury. Content and “take it slow” are largely human things. Animals just kinda… do it and it’s done.