Signalement: 12 year male neutered domestic short hair, weighing 4.5 kg.

History: The cat was referred to a veterinary hospital for further management of pneumothorax and pulmonary contusions 48 hours post blunt trauma.

Main clinical examination findings: On admission the cat was alert, ambulatory and responsive but dyspnoeic with reduced lung sounds bilaterally. The heart rate was 220 beats per minute and the systolic blood pressure was 90 mm Hg.

Diagnostic investigation and outcome: Needle thoracocentesis was performed and oxygen therapy and multimodal analgesia was initiated. Due to worsening hypercapnia the patient was anaesthetised and mechanical ventilation (MV) was initiated. Computed tomography revealed multiple rib fractures and pulmonary contusions. Venous carbon dioxide improved on MV. Epidural catheter and an oesphagostomy tube was placed prior to ventilator weaning. Despite cessation of all intravenous anaesthetic drugs and spontaneous ventilation the cat remained comatosed. The cat developed harsh lung sounds 12 hours post cessation of MV. Thoracic radiographs and endotracheal wash was consistent with Klebsiella pnuemoniae pneumonia. Intravenous antibiosis was initiated. Five days after discontinuing anaesthetic drugs the cat showed response to auditory stimuli. On day 6 post termination of MV the cat became acutely hypotensive and bradycardic with atrial premature complexes. Blood work revealed metabolic acidosis, azotaemia and hyperkalaemia. Despite therapy the cat experienced a sudden cardiac arrest and the owner declined resuscitation. A necropsy was performed. Microscopic findings revealed necrotizing adrenalitis with diffuse severe cortical haemorrhage and intralesional bacteria. The adrenal lesions were consistent with Waterhouse-Friderichsen syndrome. The brain was macroscopically and microscopically unremarkable. Culture of the epidural catheter grew Klebsiella pneumoniae.

Discussion: Acute haemorrhagic necrosis of the adrenal gland and clinical adrenal insufficiency, termed Waterhouse-Friderichsen syndrome is a rarely reported condition in people. The condition is primarily considered a complication of meningococcal septicemia, but has been associated with other bacterial pathogens including K. pnuemoniae. To the authors’ knowledge, this is the first report in veterinary medicine of Waterhouse-Friderichsen syndrome secondary to bacterial infection. This condition led to a rapid clinical deterioration and cardiac arrest in this patient. Awareness of this condition may allow for earlier recognition and appropriate treatment of this syndrome ante-mortem.