Cardiorespiratory effects of enoximone in anaesthetised colic horses.
BACKGROUND
No studies have been reported on the effects of enoximone in anaesthetised colic horses.


OBJECTIVE
To examine whether enoximone improves cardiovascular function and reduces dobutamine requirement in anaesthetised colic horses.


METHODS
Forty-eight mature colic horses were enrolled in this prospective, randomised clinical trial. After sedation (xylazine 0.7 mg/kg bwt) and induction (midazolam 0.06 mg/kg bwt, ketamine 2.2 mg/kg bwt), anaesthesia was maintained with isoflurane in oxygen and a lidocaine constant rate infusion (15 mg/kg bwt, 2 mg/kg/h). Horses were ventilated (PaCO2 < 8.00 kPa). If hypotension occurred, dobutamine and/or colloids were administered. Ten minutes after skin incision, horses randomly received an i.v. bolus of enoximone (0.5 mg/kg bwt) or saline. Monitoring included respiratory and arterial blood gases, heart rate (HR), arterial pressure and cardiac index (CI). Systemic vascular resistance (SVR), stroke index (SI) and oxygen delivery index (DO2I) were calculated. For each variable, changes between baseline and T10 within each treatment group and/or colic type (small intestines, large intestines or mixed) were analysed and compared between treatments in a fixed effects model. Differences between treatments until T30 were investigated using a mixed model (a = 0.05).


RESULTS
Ten minutes after enoximone treatment, CI (P = 0.0010), HR (P = 0.0033) and DO2I (P = 0.0007) were higher and SVR lower (P = 0.0043) than at baseline. The changes in CI, HR and SVR were significantly different from those after saline treatment. During the first 30 min after enoximone treatment, DO2I (P = 0.0224) and HR (P = 0.0003) were higher than after saline administration. Because the difference in HR between treatments was much clearer in large intestine colic cases, an interaction was detected between treatment and colic type in both analyses (P = 0.0076 and 0.0038, respectively).


CONCLUSIONS
Enoximone produced significant, but short lasting, cardiovascular effects in colic horses.


CONCLUSIONS
Enoximone's cardiovascular effects in colic horses were of shorter duration than in healthy ponies.
Schauvliege
S
S
Department of Surgery and Anaesthesia of Domestic Animals, Faculty of Veterinary Medicine, University of Ghent, Salisburylaan 133, B-9820 Merelbeke, Belgium.
Gozalo Marcilla
M
M
Gonzalo Marcilla
M
M
Duchateau
L
L
Martens
A
A
Vlaminck
L
L
Pille
F
F
Declercq
J
J
Levet
T
T
Gasthuys
F
F
D000769:Anesthesia, Inhalation / Q000662:veterinary; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output; D003085:Colic / Q000662:veterinary*; D017335:Enoximone / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006734:Horse Diseases / Q000601:surgery*; D006736:Horses; D008297:Male; D010100:Oxygen / Q000097:blood; D012119:Respiration / Q000187:drug effects*; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
D014665:Vasodilator Agents; D017335:Enoximone; D010100:Oxygen