Infectious Diseases

Avast, Ye Swabs! Mucosal Testing May Help Streamline Response to EHV Infection

By Adam Marcus

Nasal swabs may not be everyone’s idea of a good time, but Bettina Wagner, DVM, PhD, and her colleagues are more than a little enthused about the oversized Q-tips.

The reason: New data from Dr. Wagner’s group show that nasal swabbing can provide early evidence of infection—or a lack thereof—in horses exposed to a range of pathogens in the stable. In a recent study, the researchers reported that antibody samples obtained from equine mucosa reliably identified horses exposed to equine herpes virus-1 (EHV-1). Nasal swabs could help stables better manage outbreaks of the virus when combined with clinical monitoring, polymerase chain reaction (PCR) testing, and blood analysis for serum antibodies to detect previously infected animals.

Dr. Wagner, the James Law Professor of Immunology at the Cornell College of Veterinary Medicine in Ithaca, N.Y., said the idea for using nasal swabs to manage EHV-1 came during an outbreak of the infection at Cornell in 2024.

Typically, stables affected by EHV-1 won’t know the virus is circulating until an animal develops neurologic signs of infection, such as the inability to stand, which generally occurs 7 to 10 days after exposure. For stables with many horses, the obvious questions are, “Which other animals are affected and need to be quarantined?” and “Which have developed immunity to EHV-1 through prior infection and do not require special protections?”

Taking blood samples in the middle of an outbreak can reveal which animals have antibodies against the virus, Dr. Wagner said, but that does not help predict which ones will get sick and which are already immune.
Prior research in Dr. Wagner’s lab at Cornell had shown horses previously infected with EVH-1 exhibited large spikes in antibody titers in the nasal mucosa, but not in serum. But would the same be true in a natural outbreak?

The answer was yes.

“We did see those spikes in the natural outbreak, which was very cool,” Dr. Wagner said. “I was really excited when I saw the results.”

Dr. Wagner acknowledged that mucosal antibody detection is not quite ready for onsite use during outbreaks. “Nasal swabs are regularly taken for PCR to make the EHV-1 diagnosis in an outbreak. The antibody testing can be done on the same sample,” she said. But for the moment, the samples must be run in a laboratory capable of performing enzyme-linked immunosorbent assay (ELISA) multiplex assays—instead of conventional ELISA immunoassays.

She added that the Animal Health Diagnostic Center at Cornell is capable of doing the work.
Time is also a key factor. “If you want to do it, then you need to do the sampling early, when the first case is diagnosed,” she said.

A final hitch is that not all horses enjoy nasal swabs, and swabbing requires at least 2, and sometimes 3, samples per animal.

But the potential advantages over existing procedures are clear: “You are able to identify horses with preexisting immunity that won’t get sick, and you can focus on horses that might be more vulnerable to getting the virus,” she said. That narrower attention could translate to a targeted approach for expensive antivirals or other treatments for the horses at risk, she added. MeV

For more information:
Perkins GA, Wagner B, Rollins A, et al. Serum and mucosal antibody testing to detect viral exposure in contact horses during an equine herpesvirus myeloencephalopathy outbreak. Am J Vet Res. 2025;86(9)
https://avmajournals.avma.org/view/journals/ajvr/86/9/ajvr.25.03.0106.xml