Abstract
Objectives The use of physiological parameters such as respiratory rate and heart rate to assess pain has long been discussed. The aim of the study was to compare postoperative respiratory rate and heart rate in cats subjected to flank ovariohysterectomy treated with a preoperative non-steroidal anti-inflammatory drug (NSAID) or no NSAID, and determine whether these parameters are suitable for postoperative pain assessment in cats. We hypothesised that cats without an NSAID would experience more postoperative pain, which may increase heart rate and respiratory rate. Methods A total of 168 female privately owned cats were studied. All cats were premedicated with medetomidine (0.08 mg/kg) and butorphanol (0.4 mg/kg) subcutaneously and anaesthesia was induced with intramuscular ketamine (5 mg/kg). Cats were divided into subgroups; controls (no NSAID) or cats given an NSAID, carprofen (4 mg/kg) or meloxicam (0.3 mg/kg), at premedication or induction of anaesthesia. Cats were subjected to flank ovariohysterectomy by the same surgeon. Atipamezole was administered 2.5 h after induction of anaesthesia. Respiratory rate and heart rate were measured 3.5 h after the induction of anaesthesia. Data were analysed using one-way ANOVA with mixed procedure and Tukey's adjustment method for multiplicity. Results The postoperative respiratory rate and heart rate per minute for all cats were 34.0 ± 8.6 and 167.5 ± 27.4, respectively. Neither respiratory rate nor heart rate differed significantly between the control group and the NSAID groups or between different time points of administration of NSAIDs. Conclusion and relevance Assuming there was less postoperative pain in the group administered NSAIDs, the results of the study presented no support for use of respiratory rate and heart rate as parameters for postoperative pain assessment in individual cats. Study limitations included a lack of pain scoring and baseline data for respiratory rate and heart rate.