Proceeding of the 35 scientific conference of Tanzania veterinary Association, Vol. 35: 147-152A 4-year-old East African black headed ewe was presented to Sokoine University of Agriculture Animal Hospital with a history of loss of body condition and respiratory distress. Clinical examination revealed poor body condition, severe leukopenia with neutrophilia and lymphopenia. Radiographic examination of the thorax revealed an elongated caudal mediastinal mass with soft tissue opacity dorsal to caudal vena cava and caudal to the carina. The ewe was humanely euthanised due to deteriorated body condition. At post-mortem examination the mass contained caseous creamy material with early laminated appearance surrounded by a whitish fibrous capsule suggestive of chronic abscessation of caudal mediastinal lymph node. Corynebacterium pseudotuberculosis was isolated on bacterial culture of pus sample. A diagnosis of an abscessed caudal mediastinal lymph node as a result of Corynebacterium pseudotuberculosis infection was made. Thoracic radiography should be considered in sheep with chronic progressive emaciation and respiratory distress. Further, in sheep with caudal mediastinal mass, caseous lymphadenitis should be considered as one of the differential diagnoses.