Think of this as yoga/yoga nidra for your horse.
Just like in people, horses hold physical and emotional tension in their body. You need to address the cause of the problem (training issue, hoof issue, dental issue, medical issue, etc), but you also need to address the underlying tension that developed in the body as a result of the issue.
To learn more about yoga/yoga nidra and polyvagal theory to address tension you may have, click here
Masterson Method Massage
Murdock Method-Sure Foot