I disagree. Second degree heart block is quite common in horses,
particularly healthy and fit horses. Dropped beats are not at all unusual.
They are due to vagal tone, and are usually easily abolished by startling
the horse , or by jogging it for a short distance.
In addition, to quote John Bonagura, from "Current Therapy in
Equine Medicine 4":
"Arterial blood pressure can be regulated durin inappropriate
periods of sinus tachycardia by blocking impulses in the AV node
even as the
sinus rate increases. Examples include a horse that has suddenly
stopped submaximal exercise...must be appreciated as variations of
Sounds like a distance horse at a vet check, no?