Stephen J. Birchard DVM, MS, Diplomate ACVS

Monday, May 19, 2014

Postoperative Pain Control in Dogs and Cats: How much is enough?

Postoperative comparison of four perioperative analgesia protocols in dogs undergoing stifle joint surgery
Kerrie A. Lewis, DVM, MS; Richard M. Bednarski, DVM, MS; Turi K. Aarnes, DVM, MS;
Jonathan Dyce, MA, VetMB; John A. E. Hubbell, DVM, MS
(J Am Vet Med Assoc 2014;244:1041–1046)


In this study the authors compared 4 protocols for perioperative analgesia in dogs undergoing TPLO surgery for the treatment of a ruptured cruciate. Forty-eight dogs were included in the study. The dogs were randomly assigned to receive one of the following protocols:
            IM premedication with morphine
            CRI of morphine, lidocaine, and ketamine (MLK)
            Lumbosacral epidural of morphine and ropivicaine
            Both MLK and the epidural of morphine and ropivicaine.

All dogs received NSAIDS after surgery. Pain and sedation scores were collected from the dogs for 24 hours postoperatively. Morphine was administered as a rescue analgesic if a pain score of > 5 of 24 was determined.

No differences in anesthetic parameters were found between groups, and no differences in postoperative pain parameters (pain scores, sedation score, rescue analgesia requirement, or time to first rescue analgesia administered after surgery) were found. The authors concluded that all 4 analgesic protocols were acceptable for postoperative analgesia for the first 24 hours.


The most conservative analgesic protocol, i.e., premedication with morphine alone, was as effective as the more aggressive protocols. Based on the results of this study, the conservative approach of an opiod premedication combined with postoperative NSAID therapy appears to be an appropriate method of pain control in dogs having TPLO.

This well designed study provides us with valuable clinical information. The authors chose dogs having TPLO, which is a painful surgical procedure involving osteotomy of the proximal tibia followed by plate fixation. The fact that 1 preoperative dose of morphine combined with postoperative non-steroidal therapy provided acceptable postoperative analgesia suggests that more aggressive pain management may not be necessary.

The findings of this study bring up a larger question: what is the appropriate level of pain control for postoperative patients? How much analgesic therapy is needed after other types of surgeries such as abdominal or thoracic procedures?   An aggressive approach to pain management ensures that we are addressing the needs of the patient, however, all medications have side effects and these must be considered when formulating our approach.  Regurgitation, aspiration pneumonia, dysphoria and excessive sedation are all complications that are associated with drugs used for analgesia.  The subjective nature of our pain assessment methods makes it difficult to know when we are administering an appropriate amount of analgesia. Hopefully more studies like this one in which objective measures were used to assess sedation and pain will be conducted to answer these questions.

What is your opinion? What routine analgesic protocols do you use and what is your experience with them? Leave a comment on the blog or on facebook; I would love to hear your thoughts.            

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