title: Propofol anaesthesia for surgery in late gestation pony mares.
abstract: OBJECTIVE
  To characterize propofol anaesthesia in pregnant ponies.
  
  
  METHODS
  Fourteen pony mares, at 256 ± 49 days gestation, undergoing abdominal surgery to implant fetal and maternal vascular catheters.
  
  
  METHODS
  Pre-anaesthetic medication with intravenous (IV) acepromazine (20 µg kg-1), butorphanol (20 µg kg-1) and detomidine (10 µg kg-1) was given 30 minutes before induction of anaesthesia with detomidine (10 µg kg-1) and ketamine (2 mg kg-1) IV Maternal arterial blood pressure was recorded (facial artery) throughout anaesthesia. Arterial blood gas values and plasma concentrations of glucose, lactate, cortisol and propofol were measured at 20-minute intervals. Anaesthesia was maintained with propofol infused initially at 200 µg kg-1minute-1, and at 130-180 µg kg-1minute-1after 60 minutes, ventilation was controlled with oxygen and nitrous oxide to maintain PaCO2between 5.0 and 6.0 kPa (37.6 and 45.1 mm Hg) and PaO2between 13.3 and 20.0 kPa (100 and 150.4 mm Hg). During anaesthesia flunixin (1 mg kg-1), procaine penicillin (6 IU) and butorphanol 80 µg kg-1were given. Lactated Ringer's solution was infused at 10 mL kg-1hour-1. Simultaneous fetal and maternal blood samples were withdrawn at 85-95 minutes. Recovery from anaesthesia was assisted.
  
  
  RESULTS
  Arterial blood gas values remained within intended limits. Plasma propofol levels stabilized after 20 minutes (range 3.5-9.1 µg kg-1); disposition estimates were clearance 6.13 ± 1.51 L minute-1(mean ± SD) and volume of distribution 117.1 ± 38.9 L (mean ± SD). Plasma cortisol increased from 193 ± 43 nmol L-1before anaesthesia to 421 ± 96 nmol L-160 minutes after anaesthesia. Surgical conditions were excellent. Fetal umbilical venous pH, PO2and PCO2were 7.35 ± 0.04, 6.5 ± 0.5 kPa (49 ± 4 mm Hg) and 6.9 ± 0.5 kPa (52 ± 4 mm Hg); fetal arterial pH, PO2and PCO2were 7.29 ± 0.06, 3.3 ± 0.8 kPa (25 ± 6 mm Hg) and 8.7 ± 0.9 kPa (65 ± 7 mm Hg), respectively. Recovery to standing occurred at 46 ± 17 minutes, and was generally smooth. Ponies regained normal behaviour patterns immediately.
  
  
  CONCLUSIONS
  Propofol anaesthesia was smooth with satisfactory cardiovascular function in both mare and fetus; we believe this to be a suitable anaesthetic technique for pregnant ponies.
authors.affiliation: University of Cambridge, Department of Clinical Veterinary Medicine, Cambridge, UK. Electronic address: pmt12@cam.ac.uk.
authors.forename: Polly M
authors.initials: PM
authors.lastname: Taylor
authors.affiliation: University of Cambridge, Department of Clinical Veterinary Medicine, Cambridge, UK.
authors.forename: Kate L
authors.initials: KL
authors.lastname: White
authors.affiliation: University of Cambridge, Physiological Laboratory, Cambridge, UK.
authors.forename: Abigail L
authors.initials: AL
authors.lastname: Fowden
authors.affiliation: University of Cambridge, Physiological Laboratory, Cambridge, UK.
authors.forename: Dino A
authors.initials: DA
authors.lastname: Giussani
authors.affiliation: University of Cambridge, Physiological Laboratory, Cambridge, UK.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Bloomfield
authors.affiliation: Nuffield Department of Anaesthetics, University of Oxford, UK.
authors.forename: John W
authors.initials: JW
authors.lastname: Sear
keywords: anaesthesia; intravenous; ponies; propofol