J.D. Wheat Veterinary Orthopedic Research Laboratory, Department of Anatomy, Physiology and Cell Biology, University of California, Davis, CA.
Pulmonary Ultrasonographic Abnormalities Associated with Naturally Occurring Equine Influenza Virus Infection in Standardbred Racehorses
Article first published online: 5 FEB 2008
© 2004 American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 18, Issue 5, pages 718–727, September 2004
How to Cite
Gross, D. K., Morley, P. S., Hinchcliff, K. W., Reichle, J. K. and Slemons, R. D. (2004), Pulmonary Ultrasonographic Abnormalities Associated with Naturally Occurring Equine Influenza Virus Infection in Standardbred Racehorses. Journal of Veterinary Internal Medicine, 18: 718–727. doi: 10.1111/j.1939-1676.2004.tb02611.x
- Issue published online: 5 FEB 2008
- Article first published online: 5 FEB 2008
- Revised November 18, 2003; Accepted May 7, 2004
- Infectious upper respiratory disease;
- Upper respiratory disease
The purpose of this investigation was to determine if naturally occurring acute infectious upper respiratory disease (IRD) caused by equine influenza virus is associated with ultrasonographically detectable pleural and pulmonary abnormalities in horses. Standardbred racehorses were evaluated for signs of IRD, defined as acute coughing or mucopurulent nasal discharge. For every horse with IRD (n = 16), 1 or 2 horses with no signs of IRD and the same owner or trainer (n = 30) were included. Thoracic ultrasonography was performed within 5–10 days of the onset of clinical disease in horses with IRD. Horses without IRD were examined at the same time as the horses with IRD with which they were enrolled. The rank of the ultrasound scores of horses with IRD was compared to that of horses without IRD. Equine influenza virus was identified as the primary etiologic agent associated with IRD in this study. Mild lung consolidation and peripheral pulmonary irregularities were found in 11 (69%) of 16 of the horses with IRD and 11 (37%) of 30 of control horses. Lung consolidation (median score = 1) and peripheral irregularities scores (median score = 1) were greater in horses with IRD compared to horses without IRD (median score = 0; P < .05). Pleural effusion was not observed. Equine influenza virus infection can result in abnormalities of the equine lower respiratory tract. Despite the mild nature of IRD observed in this study, lung consolidation and peripheral pulmonary irregularities were more commonly observed in horses with clinical signs of IRD. Further work is needed to determine the clinical significance of these ultrasonographic abnormalities.