Radius-ulna fracture in a one-year-old Labrador retriever.Photo courtesy Phil Zeltzman Perhaps one of my favorite sayings has to be “pain is not acceptable.” We are able to perform some incredibly invasive procedures, including combined abdominal and thoracic surgery, “half-face-ectomies” and amputations. Despite the invasiveness of the surgery, it is possible that we can have patients recover smoothly, quietly, and comfortably. Let’s review six pain management modalities any enlightened practitioner can implement in everyday practice. Let’s also review six important philosophies related to pain management. 1) Opioids Opioids are the cornerstone of modern pain management. They provide excellent pain control, have sedative properties, and have a sparing effect on anesthesia. Of course, this is assuming you choose the proper opioid. Butorphanol is a weak, short-acting opioid that doesn’t have a huge place in veterinary medicine. It’s better at sedation than pain management. It provides limited somatic analgesia and very short-lived visceral analgesia. It also has a ceiling effect, which means that giving more will not provide better analgesia, but will increase its side effects. Its use can also counteract the effect of stronger opioids you may want to use afterward. Buprenorphine is very convenient in its oral form in cats, and its long-acting form (24-hour and 72-hour formulations). Modern analgesia is more likely to use drugs like hydromorphone and fentanyl, which have been shown to be easy and safe to use. Opioid Constant Rate Infusions (CRIs) are a great way to use sustained pain management before, during, and after surgery. A fentanyl patch, when wisely positioned (e.g. limb extremity), can be used strategically as part of a comprehensive analgesia protocol. 2) Ketamine Ketamine, an N-methyl-D-aspartate (NMDA) antagonist, is a mild analgesic that can modulate central sensitization. It is best used in combination with other drugs, such as benzodiazepines (diazepam, midazolam) for induction. 3) Blocks Local blocks should be used in every location conceivable. Their efficacy has been shown in testicular blocks, epidurals, brachial plexus blocks, radial/ulnar/median nerve blocks, intra-articular, retrobulbar, infiltrative blocks (e.g. linea alba), intercostal blocks, intraperitoneal blocks, and splash blocks. Local anesthetics are safe, cheap, and easy to use. The most common ones are lidocaine and bupivacaine. A more advanced and potent, albeit costlier, long-acting local block is in the form of liposome-encapsulated bupivacaine (Nocita). It numbs the surgical site for up to three days. Other interesting techniques include a lidocaine patch and a soaker catheter. 4) Dexmedetomidine The main alpha-2 adrenoceptor agonist used these days is dexmedetomidine, either as part of multimodal analgesia, or as a “rescue drug” after surgery. A useful benefit is that it can be reversed with atipamezole, if needed. 5) Orals A variety of oral drugs can be used before and after surgery: NSAIDs, gabapentin, amantadine and tramadol are probably the most commonly used oral medications. Many colleagues use NSAIDs and gabapentin in combination. Tramadol seems to slowly fade in the collective memory of those who understand its true benefits (or lack thereof) and who have largely replaced it by gabapentin. 6) Non-pharmacologic There are countless ways to provide analgesia without chemicals. Some of these modalities, used alone or in combination, include physical therapy, weight control, joint supplements, environment modification, postop confinement, controlled activity, massage, cryotherapy, and heat therapy. Of course, there are other modalities that are more or less controversial. Some of the above pain management techniques require skills and practice. Most are simple and easy to perform. Add them to your repertoire, and your patient will have a much better experience at your practice. Now let’s review six basic principles of pain management. 1) Score The pain score has been dubbed the fifth vital sign in human medicine, after TPR and blood pressure. Pain scoring is quick and simple, and should absolutely be part of any modern practice. Sadly, pain is invisible, and, therefore, often ignored. The Colorado Pain Scale, which uses five numbers (from zero to four) is likely the easiest one to implement in general and specialty practice. 2) Preemptive There seems to be a stubborn myth that you must do a physical exam, blood work, and X-rays before giving a patient the benefit of pain relief, for example a hit-by-car. Yet, there is virtually no situation in which pain medications should be withheld. Adopt the opposite philosophy: Give pain medications first, then do your exam, blood work, and X-rays, all of which can ironically cause more pain. 3) Multimodal A multimodal approach allows using smaller dosages of complementary drugs. The most often drugs include NSAIDs, local anesthetics, opioids, alpha-2 adrenoceptor agonists (dexmedetomidine), and NMDA antagonists (ketamine). Combining some of these drugs provides synergistic benefits. For example, it’s not unusual to run anesthesia at 1 percent isoflurane or less with an appropriate analgesic cocktail. 4) Comfort It is wise to spend some time thinking about each patient’s overall comfort: heat support, proper hydration, thick bedding, nausea (maropitant, which incidentally may provide pain relief as well), etc. 5) Monitor Pain management should not be a rigid, universal recipe. Instead, it should be reasoned and adapted to each patient’s specific situation, including preop pain score, invasiveness of the procedure, and concurrent health conditions. Like the depth of anesthesia, opioids should be titrated. Increase or decrease the rate of the CRI to fit the patient’s requirements. Something else to carefully monitor is effects of NSAIDs on the liver and the kidneys. Regular blood work should be performed every six months. Patients on NSAIDs who are at risk for kidney or liver disease should have blood work every two to four months. 6) Lean weight Dosing analgesic drugs should be calculated for lean weight rather than actual weight. There is a paucity of information, but a good rule of thumb to follow is to decrease the dosage proportionally to the amount of overweight. For example, if a patient is 20 percent overweight, then decrease the dosage by 20 percent. This is especially true for drugs that are highly polar, a.k.a. water soluble, since they do not distribute to fat. Analgesia is not limited to surgery patients. Medical conditions such as pancreatitis, cancer, otitis, dental disease, and osteoarthritis are painful, too. Apply the above principles to every patient you see. Every single one should be pain scored, and treated accordingly. Pain management should be a practice-wide awareness, rather than an afterthought (or worse: a choice made by the client). Veterinary nurses should be empowered to play an active role in pain management. After all, the veterinary oath includes “the prevention and relief of animal suffering.” Phil Zeltzman, DVM, DACVS, CVJ, Fear Free Certified, is a board-certified veterinary surgeon and serial entrepreneur whose traveling surgery practice takes him all over Eastern Pennsylvania and Western New Jersey. He also is cofounder of Veterinary Financial Summit, an online community and conference dedicated to personal and practice finance (www.VetFinancialSummit.com). AJ Debiasse, a technician in Blairstown, N.J., contributed to this article.
