Brenda K. Feller
CVT, RVT, VTS (Anesthesia and Analgesia)
Brenda graduated from Michigan State University, one of the first veterinary technician programs in the United States. She has worked in private practice, a university anesthesia department, and specialty practices during her career. She is not only a board member at large of the Academy of Veterinary Technicians in Anesthesia and Analgesia, but also a member of the academy’s examination, preapplication, and conference committees. She is married to Doug, a retired veterinarian, with three grown children and a growing number of grandchildren! Doug and Brenda share their house with a rescue Westie mix.
Brenda is a frequent speaker at major conferences and teaches online anesthesia classes. In her spare time, she likes to rollerblade and read nonfiction.Read Articles Written by Brenda K. Feller
The veterinary community is experiencing an opioid shortage, and although many rumors abound, let’s start with the facts that the Food and Drug Administration (FDA) has laid out.
The largest manufacturer of opioids in the United States, Pfizer, has been required to decrease production because of mandatory upgrades to their plant (FIGURE 1). The FDA is working with other producers to expand their production to help reduce a portion of the shortage until Pfizer is able to get back to normal production.1
The American Veterinary Medical Association (AVMA) has been closely monitoring the shortage and recommends that you contact the FDA at AskCVM@fda.hhs.gov or call them at 240-402-7002 (the office of the FDA’s Center for Veterinary Medicine) to voice your concerns. If we stay silent, the FDA will not know how profoundly this affects veterinary patients. The AVMA further suggests using adjunct therapies to help provide analgesia for your patients.
Rethinking Our Strategy
Best medicine practice has always been to provide multimodal analgesia for the patient. In the past, the veterinary profession may have relied more heavily on opioids and not used adjunct therapies to their full advantage. We need to rethink our strategy.
Obtaining pure mu opioids may still be possible, but it will take more time and effort on your part than in the past. The best option is to make requests from multiple distributors, for a variety of opioids, and to use standing orders. Veterinary healthcare teams must be willing to use different opioids and different strengths of the formerly used drugs. Examples of this include using sufentanil instead of fentanyl and using a hydromorphone concentration of 10 mg/mL instead of 2 mg/mL. This will require some updated education on your part, but it’s worth it for the analgesic results in the patient (FIGURE 2).
Those hospitals lucky enough to still have pure mu opioids in their possession should use them sparingly. One option suggested by Andrea Looney, DVM, DACVAA, is to incorporate a butorphanol and dexmedetomidine premedication and then, just before incision, administer a pure mu opioid injection. She has had good results using this method along with adjunct therapies.2
What else can be used if your supply of opioids has been depleted or diminished?
Preemptive analgesia is always the best option. One way to accomplish preemptive analgesia is with local and regional blocks. These blocks are one of the most effective ways of blocking transmission of pain.3 Common blocks include the following:
- Circumferential (ring)
- Ovarian ligament
- Multiple dental blocks
- Midhumeral block of the radial, ulnar, median and musculocutaneous (RUMM)
Most of these blocks are fairly easy to gain proficiency in, and the cost is minimal. The International Veterinary Academy of Pain Management’s 2011 position/consensus statement says: “Locoregional anesthesia should be used, insofar as possible, with every surgical procedure.” (FIGURES 3-6)4
Liposome bupivacaine (Nocita; nocita.aratana.com) is a bupivacaine liposome injectable suspension that provides analgesia for 72 hours when administered as indicated by the company. It is now approved for both feline and canine patients.
Gabapentin administered a few days before surgery seems to reduce pain, although the mode of action is unknown.
Another option is preemptive administration of nonsteroidal anti-inflammatory drugs (NSAIDs). In the past there was some concern that preemptive use of these drugs in the presence of hypotension may precipitate renal damage, but more recently there has been some evidence to question this.5 In the face of the opioid shortage, preemptive use of an NSAID might be worth considering when blood pressure is being monitored.
Use of microdoses (0.001 to 0.01 mg/kg/h) of ketamine as a continuous rate infusion or as a one-time dose has been shown to provide analgesia.
Maropitant (Cerenia; zoetisus.com) has shown promise in providing reduced minimum alveolar concentration requirements and seems to relieve visceral pain. It is thought to do so by the neurokinin-1 receptor.6 It appears to provide an anti-inflammatory response through substance P inhibition.
Dexmedetomidine provides some degree of analgesia and prolongs the duration of analgesia when used with an opioid.
Cryotherapy is an often-overlooked adjunct therapy. Research shows applying cold therapy and compression after surgery reduces pain and narcotic use in humans.7
Let’s not forget good nursing care. Patients that are wet, are sitting in soiled bedding, or need to urinate can experience enhanced discomfort. Simply expressing the bladder before recovery and ensuring dry bedding can aid in a patient’s postoperative comfort.
Commonly Accessible Drugs
Most practices have access to some common drugs.
Butorphanol is an antitussive agent that has some analgesic effects for mild pain and produces good sedation. Its duration of action is about 30 minutes.
Buprenorphine has shown good analgesic qualities in feline patients.8 It may be an excellent option, along with adjunct drugs, for feline patients at a dose of 0.02 mg/kg administered IV at least 30 minutes (because of its long onset of action) before incision. 2 With use of Simbadol (zoetisus.com) for 24-hour analgesia, the dose is 0.1 mg/kg SC, allowing 45 minutes of onset time.2 To obtain moderate analgesia in canine patients, a dose of 0.04 to 0.06 mg/kg q8-12H administered IV is required but will cause significant dysphoria; this effect may rule this drug out in canine patients.2
In the end, we must use what we have. The hope is to obtain synergism when using multiple drugs. Dr. Looney has had good experiences following the protocols in TABLE 1 in conjunction with adjunct therapies. With dexmedetomidine, she uses the lower end of the dose range for canine patients and in IV administration. Feline patients receive the higher end of the dose range. She administers dexmedetomidine and butorphanol as a premedication; then, just before incision, she administers the opioid IV.2 Dr. Looney presented a course, available on VetBloom, that includes other protocols and options for use during the opioid shortage (vetbloom.com).
Agents With No Analgesic Properties
It is just as important to understand that we use several agents in anesthesia that provide no analgesia but sedate or prevent the patient from reacting to pain. These include the following:
- Gas inhalants
- Midazolam and diazepam (used as sole agents)
These are useful agents, but they should not be confused with ones providing analgesia.
The Bottom Line
Your practice should use good multimodal protocols that incorporate premedication, induction drugs, and adjunct therapies, including opioids if you can obtain them. They are still an integral part of the analgesic cocktail, but we need to ensure we aren’t relying on opioids for the entire job of providing analgesia.
- U.S. Food and Drug Administration. Statement from Douglas Throckmorton, M.D., deputy center director for regulatory programs in FDA’s Center for Drug Evaluation and Research, on the agency’s response to ongoing drug shortages for critical products. June 19, 2018. fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm611215.htm. Accessed September 24, 2018.
- Looney A. Opioid Minimal Anesthesia. VetBloom. 2018. https://vetbloom.com/product?catalog=opioid-minimal-anesthesia. Accessed September 24, 2018.
- Goldberg ME, Shaffran N, Spelts K, et al. Locoregional analgesic blocking techniques. In: Goldberg ME, Shaffran N, eds. Pain Management for Veterinary Technicians and Nurses. Ames, IA: Wiley Blackwell; 2015: 67-92.
- Epstein M, Rodanm I, Griffenhagen G, et al. 2015 AAHA/AAFP pain management guidelines for dogs and cats. JAAHA. 2015;51(2):67-84.
- Surdyk KK, Brown CA, Brown SA. Evaluation of glomerular filtration rate in cats with reduced renal mass and administered meloxicam and acetylsalicylic acid. Am J Vet Res 2013;74(4):648-651.
- Laird JMA, Olivar T, Roza C, DeFelipe C, Hunt SP, Cervero F. Deficits in visceral pain and hyperalgesia of ice with a disruption of the tachykinin NK1 receptor gene. Neuroscience 2000;98:345-352.
- Murgier, J, Cassard X. Cryotherapy with dynamic intermittent compression for analgesia after anterior cruciate ligament reconstruction. Preliminary study. Orthop Traumatol Surg Res 2014;100(3):309-312.
- Robertson SA, Taylor PM, Lascelles BD, Dixon MJ. Changes in thermal threshold response in 8 cats after administration of buprenorphine, butorphanol and morphine. Vet Rec 2003;153(15):462-465.