The records of five dogs diagnosed with spirocercosis-associated pyothorax were retrospectively reviewed. On admission, the most common clinical findings were weakness, anorexia, depression, dyspnoea and fever. All dogs had typical oesophageal Spirocerca lupi granulomas. Contrast thoracic radiography revealed contrast material leakage from the oesophagus into the pleural cavity in two dogs only. All dogs were medically treated with broad-spectrum antibiotics, repeated chest tube drainage and thoracic lavage, and four of the dogs were treated with doramectin. One dog was euthanased due to a concurrent non-related disease at the owners request while the remaining four survived. S. lupi infection should be included in the differential diagnoses of canine pyothorax in endemic areas. Conservative medical management of pyothorax with antihelmintic medication was shown to be effective in the treatment of S. lupi-associated pyothorax.