The feeling is mutual

Mutual grooming is a common equine activity.

A pair will stand beside one another, usually head-to-shoulder or head-to-tail, 

grooming each other's neck, mane, rump or tail by gentle nipping, nuzzling or rubbing.

There's a practical aspect to mutual grooming: removing bugs, dead skin, or a winter coat that won't let go. 

Then there's the social aspect: it maintains pair bonding and can be a source of reassurance following social conflict.

George and Alan are masters of mutual grooming, particularly in the summer.

They know exactly where to scratch each other's itch.

 

I caught Hank trying to get in on the action last night.

But Alan politely told him three was a crowd.