Emerging Disease: Equine Multinodular Pulmonary Fibrosis Update

According to an inaugural, multi-center report, equine herpesvirus-5 (EHV-5) is associated with a newly recognized, potentially fatal lung disease in horses called equine multinodular pulmonary fibrosis, or EMPF.

"EMPF is an important emerging disease in horses that was first recognized in 2002", said lead author Kurt Williams, DVM, PhD, Dipl. ACVP, assistant professor in the Department of Pathobiology and Diagnostic Investigation at Michigan State University's College of Veterinary Medicine. "EMPF is characterized by a low grade fever, weight loss, and gradual exercise intolerance."

In this study, EHV-5 was identified in 100% of the 24 horses affected with EMPF, but in none of the horses included in the control group.

Williams explained, "This is the first published study describing EMPF and these results implicate EHV-5 as a contributor to the development of EMPF, but not necessarily as the cause of this disease." Ongoing research is attempting to characterize the precise role of EHV-5 in this disease.

equine multinodular pulmonary fibrosis gross pathology

Gross pathology of equine multinodular pulmonary fibrosis. The coalescing nodules of fibrosis (pale tan) are located in the alveolar region of the lungs, and often leave little unaffected lung (red-pink).

According to Rodney Belgrave, DVM, MS, Dipl. ACVIM, an internal medicine clinician at Mid-Atlantic Equine Medical Center located in Ringoes, N.J., "EMPF is an important emerging disease in the show horse population in the North Eastern United States, but has not yet been identified in racing Standardbreds or Thoroughbreds."

EMPF causes striking lung tissue changes in affected horses that are often quite advanced by the time of diagnosis, thereby requiring aggressive medical treatment.

"Affected horses treated appropriately have a fair to guarded prognosis, but can recover and return to training or a previous level of performance," said Belgrave.

Williams' study, "Equine multinodular pulmonary fibrosis: A newly recognized herpesvirus-associated fibrotic lung disease," was published in Veterinary Pathology and has previously been covered by The Horse based on a pre-publication presentation of the study results (article #10077).

 A case series by Wong, Belgrave, and colleagues is scheduled to be published in an upcoming edition of the Journal of the American Veterinary Medical Association.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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