New equine ailment identified, diagnosis difficult

National Report - 7/27/07 - A progressive new equine respiratory ailment identified by researchers has limited treatment options and a poor prognosis for affected horses.

With clinical signs similar to heaves, Equine multinodular pulmonary fibrosis (EMPF) is possibly linked to equine herpesvirus-5 -- a common disease thought to be non-pathogenic.

Characterized by coalescing nodules of fibrosis in the alveoli of the lungs, EMPF symptoms include a low-grade fever, weight loss and progressive respiratory disease that is often thought to be heaves or bacterial pneumonia. Treatment includes corticosteroids, but positive progress often takes several weeks of treatment and is complicated by the amount of time it often takes to diagnose the ailment.

"It is a clinically distinguishable syndrome," says Pam Wilkins, DVM, MS, PhD, Dipl. ACVIM, Dipl. ACVECC, associate professor of medicine at University of Pennsylvania, who has seen 10-15 cases. "The chest X-rays will show short of a diffuse bronchial interstitial pattern but laid on top of that are these nodules that you can see. When radiologists look at it, their big rule-outs are going to be fungal pneumonia and neoplasia (cancer)."

Researchers recommend veterinarians perform a bronchoalveolar lavage and an ultrasound-guided biopsy of the lung masses to support X-ray findings and look for fungal organisms before proceeding with treatment.