Fatal post‐anaesthetic pulmonary haemorrhage in a horse suffering from chronic‐active exercise‐induced pulmonary haemorrhage

Summary A 17‐year‐old Thoroughbred gelding was admitted for arthroscopic examination and lavage of the right tarso‐crural joint under general anaesthesia. Based on preanaesthetic examination, the patient was considered clinically healthy. No complications were experienced during induction and maintenance of anaesthesia. During the recovery period, the patient experienced acute pulmonary haemorrhage resulting in death. Post‐mortem examination revealed macroscopic and histopathological lesions indicative of exercise‐induced pulmonary haemorrhage (EIPH) with associated acute rupture of the pulmonary vessels (primarily venous). The cause of acute pulmonary blood vessel rupture in this case was speculated to be a result of increased transmural pressures in weakened blood vessels. Partial airway obstruction, catecholamine release, hypoxic pulmonary vasoconstriction, the use of the alpha‐2 adrenoreceptor agonists, fluid overload and blunt trauma may have led to the increase in pulmonary blood vessel transmural pressures. To the best of the authors’ knowledge, this is the first description of acute pulmonary haemorrhage in the peri‐anaesthetic period in a horse with underlying EIPH. In addition to describing the case, this case report also looks at anaesthetic management options in horses with known EIPH.