Use of Thoracoscopy in the Management of Pyothorax in Dogs and Cats

Inflammatory conditions of the pleura may be dry, serofibrinous, pyogranulomatous, or purulent. Purulent pleuritis, also referred to as pyothorax or empyema, is invariably the result of bacterial or fungal sepsis of the pleural space.

Sources of bacterial contamination include penetrating thoracic wounds, extension of bacterial pneumonia, migrating foreign bodies, esophageal perforations, extension of cervical, lumbar or mediastinal infections, and hematogenous spread. Thoracic bite wounds are frequently implicated in feline pyothorax. Inhalation and migration of a grass awn often is suspected in field dogs with pyothorax. Anaerobic bacteria and Nocardia asteroides are isolated most often from dogs with pyothorax. Nocardia and Actinomyces are very commonly associated to a foreign body. Pleural infections are almost always polymicrobic in nature. Pasteurella multocida and anaerobes are the most prevalent isolates in cats.

Pleuritis and pyothorax frequently have an insidious course and presentation may be delayed. Pyothorax occurs most commonly in young adult, male, non purebred cats and adult large breed dogs. Clinical signs result from restrictive disease, including increased respiratory rate, and shallow respiration, dyspnea. Other clinical signs include exercise intolerance, lethargy, anorexia, and fever. Physical examination reveals muffled heart sounds, decreased lung sounds, and dull percussion sounds, especially over the ventral portions of the thorax. Chronic or severe infection result in a patient in septic shock with dehydration debilitation or hypothermia.  [...]