Early analgesia after periodontal treatment in dogs: a comparison of three analgesic protocols

The analgesic effects of carprofen, morphine and bupivacaine on early oral pain after periodontal treatment in dogs have been poorly investigated. Forty-five client-owned dogs (8.5 +/- 6.4 kg and 7.8 +/- 3.2 years) scheduled for periodontal treatment were allocated to carprofen, morphine and bupivacaine groups (n = 15 each). The study was designed as a prospective, randomised, double "blinded" clinical study. Carprofen (CAR, 4 mg/kg, subcutaneously) or morphine (MOR, 0.3 mg/kg, intramuscularly) was given thirty minutes before the dogs were placed under anesthesia. Bilateral maxillary and mandibular nerve blocks were performed with bupivacaine (BUP, 1 mg/kg), after the induction of anesthesia. Dogs were anaesthetised with medetomidine-propofol-isoflurane and reversal was carried out using atipamezole. Periodontal painful sub-gingival scaling was performed in all dogs. Periodontal treatment lasted for up to one hour. A modified University of Melbourne Pain Score (UMPS, 0-28 points), Visual Analog pain Scale (VAS, 0-100 mm), plasma glucose (Glu) and serum cortisol (Cor) levels were assessed before administration of analgesics (MOR-0, CAR-0, BUP-0) and two hours thereafter, that is thirty minutes after atipamezole administration (MOR-2, CAR-2, BUP-2). Analgesia rescue with tramadol (2 mg/kg intramuscularly) was provided for animals with modified UMPS over 14 or VAS over 50 points. Differences in Glu and Cor values were analysed with analysis of variance (ANOVA) for repeated measures, in UMPS and VAS over time for each group with the Friedman test and pre- and postoperatively using the Mann-Whitney U-test. Differences were considered significant at P < 0.05. Analgesia rescue was provided to one patient of the CAR group and one patient of the MOR group. No differences in UMPS values between groups were detected. A significant increase in VAS values after treatment was detected in all groups. Plasma glucose levels significantly increased in MOR-2 compared to MOR-0 and CAR-2. Serum cortisol levels significantly increased in MOR-2 compared to MOR-0, CAR-2 and BUP-2. The results of this study indicate that bupivacaine nerve blocks could be superior to carprofen, which in turn could be superior to morphine, for early analgesia (up to two hours) following sub-gingival scaling for periodontal treatment in dogs.