Anaesthetic management for hydropool recovery in 50 horses

Summary This study retrospectively describes the anaesthetic management before and during hydropool recovery in horses. Fifty horses (mean age 113.7 ± 64.2 months, mean weight 479.3 ± 115.3 kg) underwent surgery for repair of different long bone fractures and other severe orthopaedic diseases. Thirty-nine horses were starved for 8-12 hours and eleven horses were presented as emergency cases, which needed immediate intervention. Intravenous antibiotics, acepromazine (0.03 mg/kg IM) and phenylbutazone (4 mg/kg IV) were administered 30-60 minutes before anaesthesia induction. Sedation was achieved using medetomidine (7 mcg/kg IV) and anaesthesia induction with 2.2 mg/kg ketamine and 0.02 mg/kg diazepam IV. Anaesthesia was maintained with isoflurane (in oxygen and air) and medetomidine constant rate infusion (3.5 mcg/kg/h). Horses breathed spontaneously during the whole procedure. Mean arterial blood pressure was maintained between 70 and 90 mmHg with dobutamine (< 1.25 mcg/kg/min) and lactated ringer’s solution (5-10 ml/kg/h). All horses were administered 6-10 ml/kg hetastarch (10%). For recovery, horses were lifted with a rescue sling into a hydropool (37°C), the head was supported by an inflatable cushion. In order to increase the quality of recovery the horses were given 0.1 mg/kg morphine IM, 2 mcg/kg medetomidine IV and oxygen (15 l/min) intratracheally in the hydropool. Mean duration of anaesthesia was 251.4 ± 90.2 (97-540) minutes with no major anaesthetic complications. Mean duration of horses’ recovery to a standing position outside the pool was 63 ± 20 (40-140) minutes. For one horse (withers height 185 cm) the pool was not deep enough and the horse became excited during recovery in the hydropool. During assisted recovery in a conventional recovery box it refractured its radius and was euthanized. All other horses successfully recovered. Management as described provided excellent conditions.