Recent advances have been made with respect to an emerging progressive and often fatal respiratory disease.  Termed “Equine Multinodular Pulmonary Fibrosis” the disease is characterized by the presence of multiple coalescing fibrotic nodules within the alveoli of the lung of the horse.

Clinical signs include high fevers, lethargy, anorexia, and occasionally a cough.  Despite diffuse involvement of the lungs, respiratory signs such as nasal discharge and an increased respiratory rate are not always evident.  A definitive diagnosis can only be made via PCR (Polymerase Chain Reaction) testing for a gammaherpesvirus (Equine Herpes Virus 5) on bronchoalveolar lavage fluid and lung biopsy.   

Radiographs and ultrasound of the lungs often reveal the presence of the characteristic masses within the lung tissue.  These masses are similar in appearance to masses that would be seen with fungal pneumonias or pulmonary neoplasia (cancer).  This emphasizes the need for a thorough diagnostic work-up before initiating treatment.

 
The virus has previously been believed to be non-pathogenic, in that it has not been associated with disease in the past.  Researchers at Michigan State University have developed the PCR test for the virus, and are working on determining the exact relationship between the virus and the disease.

 
Cases have been identified and treated at the Mid Atlantic by Dr. Belgrave over the past 2 years.  Through a collaborative effort with researchers at Michigan State University, University of Pennsylvania, and Iowa State University, a paper documenting the clinical presentation of the disease will be published in a peer-reviewed journal within a few months.

 
These cases typically do not respond fully to conventional antibiotic therapy.  Although in some cases a secondary bacterial component to the pneumonia may exist.  Anti-inflammatory (corticosteroids) and antiviral therapy appears to give the horse the best chance of survival.  The course of treatment ranges from 3-4 months.  Early recognition and treatment of the disease is critical for a successful outcome.