Post-operative complications in 15 dogs following surgical management of pyothorax: a retrospective...

This retrospective case series describes 15 dogs that developed post-operative complications following open surgical management of pyothorax at four referral centres in Belgium, France, Italy and the United Kingdom that were identified among 34 dogs that underwent surgical treatment for pyothorax from 2015-2023. The study population included a variety of breeds, with mixed-breed dogs (3/15; 20%), English Springer Spaniels (2/15; 13.3%) and Malinois (2/15; 13.3%) most frequently represented. Males (8/15; 53.3%) slightly outnumbered females (7/15; 46.7%). The median age at presentation was 5.7 (min 1.5, max 9) years, and the median body weight was 24.0 (min 11, max 54) kg. All dogs had received medical management for pyothorax before referral, including antibiotic therapy and, in most cases, thoracic drainage.

Computed tomography demonstrated bilateral pleural effusion in 14/15 (93.3%) dogs, with a suspected or confirmed migrating foreign body in three cases. Diffuse pleural inflammation was identified intra-operatively in 13 dogs, fibrinous adhesions in 12 dogs, and necrotic pulmonary or mediastinal tissue in 8 dogs. Intra-operative complications occurred in nearly half of the dogs (7/15; 46.7%), including intra-operative hypotension in five and iatrogenic lung injury in two.

Surgery was performed via median sternotomy alone or in combination with cranial celiotomy, and in one dog, it included a concurrent cervical exploration due to the extent of disease present. Post-operative complications were classified using a modified Clavien-Dindo system: six dogs experienced minor complications, six experienced major complications, and three experienced catastrophic complications. Major complications included recurrent pyothorax or persistence of pleural infection in six dogs and a chest wall abscess in one dog, all of which required revision surgery. Two dogs died from catastrophic complications, and one additional dog died following a second revision surgery, resulting in an overall mortality rate of 20%. The median hospitalisation period was 5 (min 4, max 38) days, and no recurrence was reported among surviving dogs at long-term follow-up.

Post-operative complications following surgery for pyothorax are relatively common and may require intensive management or repeat thoracotomy. These risks should therefore be considered during pre-operative discussions with owners, and warrant careful post-operative monitoring. Despite post-operative morbidity, 12/15 dogs that experienced complications survived and remained free of recurrence during long-term follow-up, indicating that favourable outcomes can be achieved when complications are recognised early and managed appropriately.