What's in a whinny?

I love just watching horses - and there's always something new to ponder. So today - the whinny.

The whinny is generally described as a way for horses to maintain or regain contact with each other and also as a friendly greeting. It's an effective way to attract another horse's attention over a distance, and emotions can certainly be transmitted through frequency of whinnying and different types of whinny.

I think the whinny can convey more than simple communications like 'I'm here and excited' or 'where are you, I'm scared'.

Getting video of a really interesting example isn't easy - but here's a fairly basic one. Paddy is often observed 'managing' the social life of the horses in his field - herding 'his' mares away from the other horses, and breaking up interactions between certain horses.

In this case, Paddy is some distance away from one of his field mates who is talking to a pony over the fence. Paddy hears a squeal, whinnies in response and continues to watch until the interaction is over. I have seen more extreme examples where a play fight is turning a bit serious, and a distant whinny from Paddy breaks it up immediately. This whinny could simply be attracting the other horse's attention and thus interrupting their behaviour. But I do think there is more being communicated than that.