https://www.horseandhound.co.uk/features/why-do-horses-roll-657819Sarah Clark, an equine behavioural consultant in Essex, who runs her own behavioural consultancy business, explains: “Horses roll for pleasure when they are relaxed and feel it is safe to do so. Similar to when a person yawns, rolling is evidently contagious, and you can often see more than one horse roll in sequence.”