Pyothorax in cats is usually the result of a previous penetrating bite wound. (cuvs.org)
Boothe HW (85 %), Howe LM, Boothe DM, Reynolds LA, Carpenter M. Evaluation of outcomes in dogs treated for pyothorax: 46 cases (1983 - 2001). (vetmed.auburn.edu)
In Dogs With Pyothorax Does Medical Management Alone, Invasive Medical Management, or Surgical Management Result in Better Long - term Outcome? (veterinaryevidence.org)