Clinical features, management, short‐ and long‐term outcomes for cats and dogs diagnosed with pyothorax: 103 cases (2015‐2021)

OBJECTIVES: To describe canine and feline pyothorax cases, comparing bacteriology, aetiologies and short- and long-term outcomes of medical versus surgical treatment. MATERIALS AND METHODS: Clinical records of canine and feline pyothorax cases from two UK referral centres (2015 to 2021) were retrospectively reviewed. Follow-up was obtained from referring practices' records. RESULTS: Sixty-five dogs and 38 cats were included. Medical management was used in 62% of dogs (40/65) and 76% of cats (29/38); survival to discharge was 88% (35/40) and 90% (26/29), respectively. Surgery was performed in the remainder; survival to discharge was 80% (20/25) in dogs and 78% (7/9) in cats. Among cases with follow-up, recurrence was 8% (4/51) in dogs: 5% (1/19) surgically and 9% (3/32) medically managed; and 8% (2/24) in cats: 12% (2/17) medically managed. All dogs medically managed with thoracostomy tubes receiving pleural lavage survived: 100% (16/16) versus 73% (8/11) without. Pasteurella multocida was the predominant feline isolate, in contrast to dogs that had no single dominant species. Multidrug-resistant organisms were identified in 29% (7/24) and 21% (5/24) of culture-positive canine and feline patients. Aetiologies were mostly unknown (dogs: 51%, 33/65; cats: 61%, 23/38), followed by parapneumonic spread (dogs: 17%, 11/65; cats: 16%, 6/38) and migrating foreign bodies (dogs: 17%, 11/65; cats: 8%, 3/38). CLINICAL SIGNIFICANCE: In selected cases, medical management of canine and feline pyothorax with thoracic drains yields survival to discharge and recurrence rates comparable to surgery, including cases with suspected migrating plant material. Pleural lavage during medical management is associated with improved survival in dogs.