"Uncommon condition affecting the lymphatic vessels; can be caused by either Corynebacterium pseudotuberculosis or Sporothrix schenckii, usually as the result of wound contamination. The lesions appear as nodules that develop most often on the hind legs below the hocks. The nodules eventually break down and ulcerate, releasing a thick greenish pus mixed with blood."
Notoriously dificult to treat - may need various antibiotics in combination or singly. Permenant damage is often a consequence.