# Assessing the Analgesic Efficacy of Lumbosacral Epidural Morphine in Cats Undergoing Ovariohysterectomy: A Comparative Study of Two Doses

## TL;DR

This study compares two doses of epidural morphine in cats undergoing surgery to see how well they reduce pain and the need for additional analgesics.

## Contribution

The study evaluates the effectiveness of two doses of epidural morphine in reducing postoperative analgesic requirements in cats.

## Key findings

- Epidural morphine at 0.1 and 0.2 mg/kg reduced the need for postoperative analgesia in cats.
- Higher doses of morphine were associated with fewer cats requiring rescue analgesia post-surgery.
- Intraoperative rescue analgesia was still needed in all groups despite epidural morphine administration.

## Abstract

We evaluated the analgesic and postoperative effects of epidurally administered opioids and local anesthetics in 20 cats that underwent elective ovariohysterectomy (OH). Propofol was used as the general anesthetic. The animals were divided into three groups according to the dose of the epidurally administered morphine. Therefore, it was necessary to use fentanyl to complement analgesia in all groups. Postoperatively, 83%, 28%, and 7% of the animals without morphine administration, with a lower dose of morphine, and with a higher dose of morphine, respectively, required additional analgesia. In conclusion, in cats undergoing OH, epidural morphine at the doses used did not eliminate the need for intraoperative rescue analgesia but did reduce the need for postoperative analgesia.

Opioids are administered epidurally (PV) to provide trans- and postoperative analgesia. Twenty healthy female cats aged between 6 and 24 months and weighing between 2 and 3.7 kg, undergoing elective ovariohysterectomy (OVH), were induced with propofol (8 mg/kg), followed by continuous infusion (0.1–0.4 mg/kg/min). Three groups were defined: CG (0.1 mL/kg of iodinated contrast, n = 6), G0.1 (0.1 mg/kg of morphine, n = 7), and G0.2 (0.2 mg/kg of morphine, n = 7) per VP. All received 0.1 mL/kg of iodinated contrast per VP and injection water to obtain a total of 0.3 mL/kg. Heart rate (HR), systolic blood pressure (SBP), temperature, expired CO2, oxygen saturation, and number of rescue analgesics were monitored. Postoperatively, a multidimensional scale was used to assess acute pain in cats for 12 h. The mean HR and SBP in the CG were higher at the time of maximum noxious stimulation and required fentanyl in all groups. Postoperatively, 83%, 28%, and 7% of the animals in CG, G0.1, and G0.2, respectively, received rescue analgesia. In cats undergoing OVH, epidural morphine at doses of 0.1 and 0.2 mg/kg did not prevent the need for intraoperative rescue analgesia but reduced the postoperative analgesic needed.