Abstract
Objective
To determine whether hyoscine has a sparing effect on the volume of dobutamine required
to maintain mean arterial pressure (MAP) at 70 mmHg in horses anaesthetized with halothane.
Study design
Prospective, randomized, controlled clinical trial.
Animals
Twenty adult horses weighing 507 ± 97 kg (mean ± SD), aged 10 ± 5 years.
Materials and methods
Pre-anaesthetic medication in all horses was intramuscular (IM) acepromazine (40 μg kg−1) and intravenous (IV) detomidine (0.02 mg kg−1). Anaesthesia was induced with ketamine (2.2 mg kg−1 IV) and diazepam (0.02 mg kg−1 IV), and maintained with halothane in oxygen. Horses breathed spontaneously. Flunixin
(1.1 mg kg−1 IV) was given to provide analgesia. Heart rate, ECG, invasive arterial pressure,
respiratory rate, percentage end-tidal carbon dioxide, percentage end-tidal halothane
and partial pressure of oxygen and carbon dioxide in arterial blood and blood pH were
monitored. Dobutamine was infused by an infusion pump to maintain MAP at 70 mmHg.
Horses were randomly assigned to receive saline or hyoscine (0.1 mg kg−1) IV 30 minutes after induction. The heart rate, MAP and volume of dobutamine infused
over 30-minute periods were measured and analysed statistically using a one-way anova.
Results
After administration of hyoscine, heart rate increased for 10 minutes (p < 0.01) and MAP for 5 minutes (p < 0.01). There was no difference in the volume of dobutamine infused over 30 minutes
between horses given hyoscine or saline, although there was a wide individual variation
in dobutamine requirements. No side effects of hyoscine were seen.
Conclusions
The increase in heart rate and blood pressure that occurs after 0.1 mg kg−1 hyoscine is given IV in anaesthetized horses, is of short duration and does not significantly
alter the amount of dobutamine required to maintain arterial pressure over the next
30 minutes.
Clinical relevance
The short duration of action of 0.1 mg kg−1 hyoscine IV may limit its usefulness for correction of hypotension in horses anaesthetized
with halothane. Further work is necessary to investigate the effects of higher or
repeated doses or constant rate infusions of hyoscine.
Keywords
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References
- Motility of the distal portion of the jejunum and pelvic flexure in ponies: effects of six drugs.Am J Vet Res. 1984; 45: 795-799
- Cardiopulmonary effects of combinations of medetomidine hydrochloride and atropine sulphate in dogs.Vet Rec. 1996; 138: 11-13
- Cardiac effects of atropine premedication in horses sedated with detomidine.Acta Vet Scand Suppl. 1986; 82: 131-136
- A comparison of N-butylscopolammonium bromide and butorphanol tartrate for analgesia using a balloon model of abdominal pain in ponies.Can J Vet Res. 1996; 60: 65-68
- Effects of xylazine on cecal mechanical activity and cecal blood flow in healthy horses.Am J Vet Res. 1988; 49: 720-723
- ‘Xylazine’- a new sedative for horses and cattle.Vet Rec. 1969; 85: 512-517
- Detomidine: a new sedative for horses.Equine Vet J. 1986; 18: 366-370
- Effect of spasmolytic analgesic drugs on the motility patterns of the equine small intestine.Res Vet Sci. 1983; 34: 334-339
- Retrospective assessment of dobutamine therapy for hypotension in anesthetized horses.Vet Surg. 1988; 17: 53-57
- Gastrointestinal complications associated with the use of atropine in horses.J Am Vet Med Assoc. 1983; 182: 229-231
- Dose effect and benefits of glycopyrrolate in the treatment of bradycardia in anesthetized dogs.Can Vet J. 1999; 40: 327-331
- Effect of romifidine on gastrointestinal motility, assessed by transrectal ultrasonography.Equine Vet J. 2001; 33: 570-576
- Haemodynamic changes during sedation in ponies.Vet Res Commun. 1990; 14: 309-327
- A preliminary study on the effects of atropine sulphate on bradycardia and heart blocks during romifidine sedation in the horse.Vet Res Commun. 1990; 14: 489-502
- Haemodynamic effects of hyoscine-N-butylbromide in ponies.J Vet Pharmacol Ther. 1995; 18: 13-16
- Arterial hypotension and the development of postanesthetic myopathy in halothane-anaesthetized horses.Am J Vet Res. 1987; 48: 192-197
- Alveolar-arterial oxygen tension differences in anaesthetized horses.Br J Anaesth. 1968; 40: 560-567
- Effects of dopamine, dobutamine, dopexamine, phenylephrine, and saline solution on intramuscular blood flow and other cardiopulmonary variables in halothane-anesthetized ponies.Am J Vet Res. 1998; 59: 1463-1472
- Effects of atropine on the arrhythmogenic dose of dobutamine in xylazine-thiamylal-halothane-anesthetized horses.Am J Vet Res. 1993; 54: 2099-2103
- Induction of equine postanesthetic myositis after halothane-induced hypotension.Am J Vet Res. 1989; 50: 404-410
- Effects of hyoscine-N-butylbromide given before romifidine in horses.Vet Rec. 1998; 142: 166-168
- Atelectasis causes gas exchange impairment in the anaesthetised horse.Equine Vet J. 1990; 22: 317-324
- Regional myocardial blood flow and coronary vascular reserve in unanesthetized ponies during pacing induced ventricular tachycardia.J Surg Res. 1983; 35: 119-131
- Effect of a 30-minute infusion of dobutamine hydrochloride on hind limb blood flow and hemodynamics in halothane-anesthetized horses.Am J Vet Res. 2000; 61: 1282-1288
- Effects of amitraz, several opiate derivatives and anticholinergic agents on intestinal transit in ponies.Equine Vet J. 1986; 18: 256-260
- Analgesic and spasmolytic effects of dipyrone, hyoscine-N-butylbromide and a combination of the two in ponies.Vet Rec. 1991; 129: 378-380
- Cardiopulmonary and gastrointestinal motility effects of xylazine/ketamine-induced anesthesia in horses previously treated with glycopyrrolate.Am J Vet Res. 1996; 57: 1762-1770
- The effect of glycopyrrolate on heart rate and intestinal motility in conscious horses.J Vet Anaesth. 1997; 24: 14-19
- Modification of cardiopulmonary and intestinal motility effects of xylazine with glycopyrrolate in horses.Can J Vet Res. 1997; 61: 99-107
- Cardiovascular effects of halothane in the horse.Am J Vet Res. 1978; 39: 611-615
- Effect of body posture on cardiopulmonary function in horses during five hours of constant-dose halothane anesthesia.Am J Vet Res. 1990; 51: 11-16
- Effects of a muscarinic type-2 antagonist on cardiorespiratory function and intestinal transit in horses anesthetized with halothane and xylazine.Am J Vet Res. 2004; 65: 464-472
- Effect of low-dose atropine administration on dobutamine dose requirement in horses anesthetized with detomidine and halothane.Am J Vet Res. 1997; 58: 1436-1439
- Temporal effects of an infusion of dobutamine hydrochloride in horses anesthetized with halothane.Am J Vet Res. 1998; 59: 1027-1032
Article info
Publication history
Accepted:
March 18,
2005
Received:
August 16,
2004
Identification
Copyright
© 2006 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Inc. All rights reserved.
