A 14-year-old Thoroughbred event horse presented with a history of coughing during low-level exercise. Initial work-up revealed signs consistent with Inflammatory Airway Disease (IAD) and he was treated with an inhaled bronchodilator and oral Prednisolone.
He presented again four weeks later with worsening cough, fever (102.2), and elevated fibrinogen (800 mg/dL). Trans-tracheal aspirate revealed moderate, mixed inflammation (believed to be primary) with evidence of bacterial infection (believed to be secondary).
Here is an ultrasound exam obtained in the right ninth intercostal space.
The ultrasound shows numerous comet tail artifacts which are caused by irregularities along the pleural surface. There is also a large, heterogenous area of consolidation which represents an area of cellular infiltrate into the lung parenchyma. The lungs demonstrated a very similar appearance in numerous intercostal spaces on the left and right sides.
Thoracic radiographs revealed a severe, diffuse, nodular, interstitial pulmonary pattern. Additional diagnostics included a trans-tracheal aspirate that was positive for EHV-5 as well as an ultrasound-guided lung biopsy which revealed diffuse, severe fibrosis, alveolar and interstitial mixed inflammation and type II pneumocyte hyperplasia. The clinical signs and all diagnostics were consistent with Equine Multinodular Pulmonary Fibrosis.
Despite extensive treatment with antimicrobials, antivirals and steroids, the horse's condition continued to worsen and he was euthanized 4.5 months after the onset of clinical signs.