Cranial thoracic masses in the horse: a sequel to pleuropneumonia.

The formation of cranial thoracic masses (CTM) as a sequel to infectious pleuropneumonia is described. Using ultrasound, masses were diagnosed subjectively as abscesses or loculations. Eight of 99 cases with pleuropneumonia had CTM. Clinical signs associated with the presence of a CTM included increased heart rate, jugular distention, forelimb 'pointing' and caudal displacement of the heart. Techniques used for diagnostic ultrasonographic examination of the cranial thorax are described. Five of the eight horses with CTM responded to conservative medical management; the other three required percutaneous drainage of the mass to relieve worsening signs of cardiac decompensation. Improvements in cardiovascular parameters were evident within 12 h of drainage. The indications for and limitations of invasive drainage of cranial thoracic masses are discussed.