A yawn can signal something other than boredom or drowsiness, it may mean a horse is frustrated or unhappy.
To read this article, visit: https://equusmagazine.com/horse-world/boring-yawning-54187.
Mentioned in this episode:
Equus on Audio Bumper V2
ByeBye Odor
https://info.spalding-labs.com/bbo-4oz/