Spontaneous pulmonary haemorrhage in a standing sedated horse

A 615-kg, 20-year-old, male, neutered Dutch warmblood horse was admitted for complete removal of incisor teeth under sedation. The horse was sedated with intramuscular acepromazine (0.1 mg/kg) and several intravenous detomidine boli (total dose of 0.008 mg/kg), followed by detomidine constant rate of infusion. At the beginning of the surgery (47 minutes after starting sedation), the horse retched and coughed out haemorrhagic fluid. Surgery was discontinued and profuse bleeding started from the nostrils. Mild hypoxaemia (PaO2 = 63.4 mmHg) was observed. Oxygen therapy by nasal canula (10 L/min) was started, detomidine constant rate of infusion stopped and antagonised with atipamezole given intravenous to effect (total dose of 0.14 mg/kg). The horse also received tranexamic acid. Pulmonary haemorrhage was suspected after tracheal-bronchoscopic examination. Fresh whole-blood transfusion was initiated (estimated blood loss: 4 L). Bleeding reduced gradually during the following 2 hours and the horse was monitored in the intensive care unit, with supplemented nasal oxygen. During the following 2 days, oxygen administration was gradually reduced and finally discontinued. The nasal bleeding resumed 8 days after the initial episode, but the horse was euthanased due to the uncertainty of the prognosis.