Successful management of two horses with suspected pulmonary haemorrhage in recovery from general anaesthesia.

This research study pertains to how two horses, displaying signs of pulmonary haemorrhage after undergoing general anaesthesia for surgical procedures, were successfully managed by veterinarians.

Research Context

• The research focuses on two particular cases – a 24-year-old warmblood mare (case 1) who was anaesthetized for bursoscopy, and a 12-year-old Holsteiner gelding (case 2), anaesthetized for a procedure called phacoemulsification.
• Both horses were premedicated and sedated using a combination of medications. Post-surgery, both horses showed significant signs of haemoptysis (coughing up blood).
• The condition gradually subsided after they were given injections of tranexamic acid and acepromazine. Oxygen was also supplied until the horses regained consciousness.

Anaesthesia and Medications

• All the medications that were used before, during and after the surgical procedures are listed in detail. The premedication involved a drug called acepromazine, following which the horses were sedated with intravenous medetomidine.
• The induction of anaesthesia was achieved with a ketamine-diazepam combination and isoflurane was used to maintain it. Medetomidine infusion was continued during the procedure.
• Following the surgery, an increased dosage of medetomidine was administered to counter the persistent nystagmus (involuntary eye movement) observed in both horses.

Observation and Management

• Post surgery and tracheal extubation, both horses started showing signs of haemoptysis. The research estimates that they lost more than 5% of their total blood volume as a result.
• The condition gradually subsided after being administered an intravenous solution of tranexamic acid and acepromazine, while the horses were still recumbent.
• Oxygen was also supplied via the trachea initially and then via the nasopharynx until the horses regained consciousness.

Conclusion and Suspected Causes

• Both horses survived the complication and were discharged successfully. Postanaesthetic pulmonary haemorrhage was suspected as the cause. Even though it is a rare complication, multiple causal factors have been proposed.
• Some of these possible causes include increased pulmonary vascular resistance due to the use of α adrenoceptor agonists, hypoxaemia, high catecholamine levels, respiratory obstruction and coughing leading to increased intrathoracic pressures and underlying respiratory diseases, even when they are subclinical in nature.
• In these two cases, the rapid injection of a high dose of medetomidine in recovery may have resulted in pulmonary hypertension, which in turn caused the haemorrhage observed.