title: Effect of low dose rate ketamine infusions on thermal and mechanical thresholds in conscious cats.
abstract: OBJECTIVE
  To determine the thermal and mechanical antinociceptive effects of two different subanesthetic constant rate infusions of racemic ketamine in cats.
  
  
  METHODS
  Prospective, randomized, blinded, experimental study.
  
  
  METHODS
  Eight healthy adult domestic shorthair cats (two intact females and six neutered males).
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: Barbara
authors.initials: B
authors.lastname: Ambros
authors.forename: Tanya
authors.initials: T
authors.lastname: Duke
mesh_terms: D000778:Anesthetics, Dissociative / Q000008:administration & dosage; D000818:Animals; D002415:Cats / Q000601:surgery; D016292:Procedural Sedation / Q000379:methods / Q000662:veterinary*; D005260:Female; D006358:Hot Temperature; D007262:Infusions, Intravenous; D007649:Ketamine / Q000008:administration & dosage; D008297:Male; D059225:Nociception / Q000187:drug effects; D010147:Pain Measurement / Q000379:methods / Q000662:veterinary; D017288:Pain Threshold / Q000187:drug effects*; D012881:Skin Temperature / Q000187:drug effects
chemical_list: D000778:Anesthetics, Dissociative; D007649:Ketamine
keywords: analgesia; antinociception; cats; infusion; ketamine