Effect of low dose rate ketamine infusions on thermal and mechanical thresholds in conscious cats
Version of Record online: 20 JUN 2013
© 2013 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia
Veterinary Anaesthesia and Analgesia
Volume 40, Issue 6, pages e76–e82, November 2013
How to Cite
Ambros, B. and Duke, T. (2013), Effect of low dose rate ketamine infusions on thermal and mechanical thresholds in conscious cats. Veterinary Anaesthesia and Analgesia, 40: e76–e82. doi: 10.1111/vaa.12057
- Issue online: 17 OCT 2013
- Version of Record online: 20 JUN 2013
- Manuscript Accepted: 19 NOV 2012
- Manuscript Received: 18 SEP 2012
- Companion Animal Health Fund
To determine the thermal and mechanical antinociceptive effects of two different subanesthetic constant rate infusions of racemic ketamine in cats.
Prospective, randomized, blinded, experimental study.
Eight healthy adult domestic shorthair cats (two intact females and six neutered males).
The thorax and the lower thoracic limbs of each cat were shaved for thermal (TT) and mechanical threshold (MT) testing and a cephalic catheter was placed. Three intravenous treatments of equivalent volume were given as loading dose (LD) followed by an infusion for 2 hours: (K5) 0.5 mg kg−1 ketamine followed by 5 μg kg−1 minute−1 ketamine infusion, (K23) 0.5 mg kg−1 ketamine followed by 23 μg kg−1 minute−1 ketamine infusion or (S) 0.9% saline solution. Effects on behavior, sedation scores, MT and TT were obtained prior to drug treatment and 0.25, 0.5, 0.75, 1, 1.5, 2, 2.25, 2.5 2.75, 3 hours then every 0.5 hours for 7 hours and 10, 12, 14 and 26 hours after loading dose administration.
Ketamine induced mild sedation for the period of the infusion, no adverse behavioral effects were observed. Thermal threshold was significantly higher than baseline (K5: 44.5 ± 0.7 °C; K23: 44.5 ± 0.5 °C) at 15 minutes in the K5 group (46.8 ± 3.5 °C) and at 45 minutes in the K23 group (47.1 ± 4.1 °C). In the K23 group TT was significantly increased compared to S and K5 at 45 minutes. In K5 at 15 minutes MT (9.6 ± 4.0 N) was different to baseline (6.1 ± 0.8 N) and to the S group (5.9 ± 2.3 N).
Conclusion and clinical relevance
Low dose rate ketamine infusions minimally affect thermal and mechanical antinociception in cats. Further studies with different nociceptive testing methods are necessary to assess whether ketamine could be a useful analgesic in cats.