TY - JOUR

T1 - Elaboration of a xylazine and dexmedetomidine infusion regime which provides a constant level of sedation in horses

AU - Mueller, Christina

AU - Hopster, Klaus

AU - Hopster-Iversen, Charlotte

AU - Rohn, Karl

AU - Kaestner, Sabine B. R.

PY - 2012

Y1 - 2012

N2 - The study was performed to elaborate equipotent constant rate infusion regimes of xylazine and dexmedetomidine in awake horses, which provide a constant level of sedation and may be suitable for constant rate infusion to be used as part of a total intravenous anaesthesia (TIVA) protocol in horses. Five adult, healthy university-owned horses were sedated three times for two hours with a washout period of 2 weeks between treatments. In group X the horses were sedated with 0.5 mg/kg bwt of xylazine IV, followed by a constant rate infusion (CRI) of 1 mg/kg bwt/h xylozine. In group D1 horses received a bolus of 3.5 mu g/kg bwt IV dexmedetomidine and a CRI of 5 mu g/kg bwt/h. In D2 horses were treated as horses in group D1 but received additional boli of 0.5 mg per horse of dexmedetomidine to reach the some reduction of nose-to-ground-distance of group X. Heart rate (HR), respiratory rate (RR) and nose-to-ground-distance were recorded every five minutes. Reaction to thermal stimulation of the skin over the nostrils and thermal threshold was tested. A two-way analysis of variance with repeated measurements was used to analyse data with an alpha of 5%. The dosage of dexmedetomidine used in group DI (3.5 mu g/kg bwt, IV and 5 mu g/kg bwt/h) was not equipotent to the xylazine dosage used in group X (0.5 mg/kg bwt, IV and 1 mg/kg bwt/h) and a calculated CRI of 7 mu g/kg bwt/h was necessary in group D2 to receive equisedation. All horses developed signs of mild to deep sedation including moderate ataxia. HR and nose-to-ground distance decreased significantly from baseline to sedation in all groups. RR decreased significantly from baseline to sedation in group D2. Thermal thresholds increased significantly above baseline from time 15 to 120 minutes in group X and DI and from time 15 to 150 minutes in group D2. We concluded that all three dosing regimes are suitable to maintain a constant level of sedation with moderate signs of ataxia. A calculated CRI of 7 mu g/kg bwt/h dexmedetomidine after a bolus of 3.5 mu g/kg bwt was equisedative to a CRI of 1 mg/kg bwt/h xylazine after a bolus of 0.5 mg/kg bwt.

AB - The study was performed to elaborate equipotent constant rate infusion regimes of xylazine and dexmedetomidine in awake horses, which provide a constant level of sedation and may be suitable for constant rate infusion to be used as part of a total intravenous anaesthesia (TIVA) protocol in horses. Five adult, healthy university-owned horses were sedated three times for two hours with a washout period of 2 weeks between treatments. In group X the horses were sedated with 0.5 mg/kg bwt of xylazine IV, followed by a constant rate infusion (CRI) of 1 mg/kg bwt/h xylozine. In group D1 horses received a bolus of 3.5 mu g/kg bwt IV dexmedetomidine and a CRI of 5 mu g/kg bwt/h. In D2 horses were treated as horses in group D1 but received additional boli of 0.5 mg per horse of dexmedetomidine to reach the some reduction of nose-to-ground-distance of group X. Heart rate (HR), respiratory rate (RR) and nose-to-ground-distance were recorded every five minutes. Reaction to thermal stimulation of the skin over the nostrils and thermal threshold was tested. A two-way analysis of variance with repeated measurements was used to analyse data with an alpha of 5%. The dosage of dexmedetomidine used in group DI (3.5 mu g/kg bwt, IV and 5 mu g/kg bwt/h) was not equipotent to the xylazine dosage used in group X (0.5 mg/kg bwt, IV and 1 mg/kg bwt/h) and a calculated CRI of 7 mu g/kg bwt/h was necessary in group D2 to receive equisedation. All horses developed signs of mild to deep sedation including moderate ataxia. HR and nose-to-ground distance decreased significantly from baseline to sedation in all groups. RR decreased significantly from baseline to sedation in group D2. Thermal thresholds increased significantly above baseline from time 15 to 120 minutes in group X and DI and from time 15 to 150 minutes in group D2. We concluded that all three dosing regimes are suitable to maintain a constant level of sedation with moderate signs of ataxia. A calculated CRI of 7 mu g/kg bwt/h dexmedetomidine after a bolus of 3.5 mu g/kg bwt was equisedative to a CRI of 1 mg/kg bwt/h xylazine after a bolus of 0.5 mg/kg bwt.

KW - equine

KW - xylazine

KW - dexmedetomidine

KW - sedation

KW - CRI

KW - anesthesiology

KW - TOTAL INTRAVENOUS ANESTHESIA

KW - DETOMIDINE

KW - PONIES

KW - MEDETOMIDINE

KW - KETAMINE

KW - PHARMACOKINETICS

KW - INVOLVEMENT

KW - GUAIFENESIN

KW - ANALGESIA

KW - PROPOFOL

M3 - Journal article

VL - 28

SP - 668

EP - 674

JO - Pferdeheilkunde

JF - Pferdeheilkunde

SN - 0177-7726

IS - 6

ER -