Moving from horse to horse and barn to barn, farriers are in a key position to recognize equine respiratory diseases, notify horse owners and take steps to help prevent the spread of such illnesses.

The threat is real. For example, although the often-fatal equine herpesvirus myeloencephalopathy (EHM) is considered rare, as of this writing there were confirmed, active cases in Texas, South Dakota, North Dakota, Michigan and California, along with a suspected case in Wyoming. Some of the afflicted animals had traveled to horse events far from home before their diagnosis, potentially carrying the danger across state lines.

This list is not comprehensive. It’s a sampling compiled from the Equine Disease Communication Center at Equine DiseaseCC.org, a voluntary reporting site affiliated with the American Association of Equine Practitioners (AAEP). There is no national database for these equine diseases, so the exact number of cases cannot be known.

More worrisome, EHM, a neurological disease, is thought to develop…