Rhodococcus equi-associated necrotizing lymphadenitis in a llama.

A case of Rhodococcus equi-associated necrotizing lymphadenitis in a 2-year-old male llama is described. Caseous necrosis, resembling macroscopically that seen in ovine caseous lymphadenitis, was observed diffusely in the tracheobronchial and mediastinal lymph nodes, and in an extensive lesion in the lungs. Necrosis was present to a lesser extent in the spleen and hepatic and gastric lymph nodes. Numerous bacteria-laden macrophages were present around the necrotic areas. The findings suggest that, as in cattle and pigs, the primary targets of R. equi infection in the llama are the lymphoid organs.