Opioid analgesics represent an important part of acute, perioperative pain management in veterinary medicine. Many veterinarians in private practice are having trouble obtaining fentanyl, morphine, hydromorphone and methadone. These represent the most commonly used pure mu opioid agonists in many veterinary hospitals. The AVMA released a statement on 2/26/18 noting the opioid shortages affecting many veterinarians since late 2017 will persist into 2019. As such, veterinarians may be presented with the challenge of needing to modify their acute and/or perioperative pain management protocols including pure mu opioid analgesics.
A general approach to such modifications is to use a multimodal approach, including the use of opioids, alpha-2 agonists, NMDA antagonists, and local anesthesia in combination when possible.
Preanesthetic Sedation
Developing a protocol with analgesic and sedative combinations (neurolept analgesia) to provide preanesthetic sedation and preemptive analgesia is still feasible with medications currently available to veterinarians. Therefore, if pure mu opioid agonists are unavailable, alpha-2 agonists (i.e. dexmedetomidine) may be administered in young, healthy patients who do not have cardiovascular disease. Co-administration with an opioid (for example, butorphanol, buprenorphine, fentanyl patch administered the day prior) will improve the quality of sedation.
Intraoperative Analgesia
Local anesthetic techniques, for example targeted nerve block and local/regional anesthesia, should be utilized whenever possible.
In general, the total local anesthetic dose administered should not exceed 6 mg/kg lidocaine or 2 mg/kg bupivacaine to avoid local anesthetic toxicity.
An intravenous bolus dose of an analgesic followed by a constant rate infusion (CRI) for longer procedures may be utilized intraoperatively to treat breakthrough pain.
- Ketamine (0.5-1.0 mg/kg IV bolus/loading dose)
- +/- CRI: intra-op 10 ug/kg/min - post-op 2-5 ug/kg/min
- Dexmedetomidine (0.5-2.0 ug/kg IV bolus/loading dose)
- +/- CRI: intra-op 1.0-2.0 ug/kg/hr - post-op 0.5-1 ug/kg/hr
- Lidocaine (1-2 mg/kg IV bolus/loading dose)
- +/- CRI: 50 ug/kg/min
Postoperative Analgesia
In addition to the CRIs Ketamine, Dexmedetomidine, and Lidocaine, that can be continued in the post-operative period, animals having had an effective local anesthetic block can be administered oral analgesics as soon as oral medications are tolerated.
Nonsteroidal analgesics, tramadol, gabapentin, or other newer analgesics such as grapiprant are examples of oral analgesics that may be considered, depending on the mechanism and severity of anticipated pain.
Questions about New Ways to Manage a Patient’s Acute and/or Perioperative Pain?
The recent opioid shortages make it necessary for veterinarians to consider new medication combinations to manage acute, perioperative pain. If you have a question regarding ways to manage your Patient’s acute and/or perioperative pain, call your local MedVet or visit us online at www.medvetforpets.com.
