Robert M. Stein, DVM, DAAPM, and Stephanie Ortel, LVT, BVS, CCRP
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Prevailing research strongly supports incorporating pain management into all aspects of patient care from birth to the end
of life. The pain pathways have their own unique version of memory, and inadequate pain management can have lasting consequences.
For example, in people, if painful experiences are inadequately addressed early in life, patients presented for subsequent
routine care may be fearful and may have enhanced pain responses as they age.1,2 If perioperative pain is not controlled through balanced analgesic methods and meticulous surgical technique, the risk of
chronic postsurgical pain increases significantly.3 Anesthetic protocols devoid of analgesic and sedative influence, such as mask induction and maintenance, may minimize patient
recovery time, but they can compromise patient comfort and safety.
Medications alone cannot provide the best possible patient quality of life and maximum longevity. These optimal goals require
integrated, multidisciplinary, multimodal pain management methods. We consider the 10 points below to be key aspects of any
well-balanced veterinary pain management program.
1 Preemptive analgesia
While an anesthetized patient is not consciously aware of pain, nociceptive pathway activation and subsequent sensitization
proceed unabated. Once the pain system has become sensitized, it is difficult to gain control of a patient's pain, requiring
higher drug doses and more complex pain management strategies. To maximize pain control and minimize adverse effects, medications
need to have taken effect before any painful stimulus occurs.
Stress influences a patient's pain experience and morbidity, making stress reduction a key—often overlooked—aspect of overall
pain management. Highly stressed patients should receive sedatives when admitted and repeated doses as needed to maintain
adequate anxiolysis before their procedures.
2 Multimodal analgesia
Effective pain management requires a combination of agents that not only target various aspects of the pain pathways but also
target patient stress to provide a balanced, multimodal effect.
Opioids are the foundation of multimodal perioperative analgesia. They have analgesic activity peripherally and centrally.
Mu agonists such as morphine, hydromorphone, and methadone and the partial mu agonist buprenorphine are our preferred presurgical
opioids. The kappa agonists butorphanol and nalbuphine are best suited for sedation for nonpainful procedures.
Midazolam, a benzodiazepine, is also an excellent premedication component. Unlike diazepam, midazolam is well-absorbed intramuscularly.
Midazolam provides additional sedative effects as well as analgesic benefit, and there is reason to believe that some patients
given midazolam experience short-term amnesia, reducing their awareness of the hospital experience. In addition, most of our
healthy patients require a third premedication component—acepromazine, medetomidine, or dexmedetomidine (Dexdomitor—Pfizer
Animal Health).
Local anesthetics can almost always be included for enhanced patient comfort and safety. Nonsteroidal anti-inflammatory drugs
(NSAIDs) are of marked patient benefit if the patient is NSAID-tolerant and blood pressures are effectively monitored and
maintained. Low-dose intravenous infusions of the N-methyl-D-aspartate (NMDA) antagonist ketamine, which blocks glutamate
receptors, inhibits central sensitization and completes a balanced perioperative pain management strategy.
Oral multimodal outpatient strategies often include several complementary analgesics. Tramadol is a generally well-tolerated
oral opioid. NSAIDs are attractive if proper attention is paid to patient selection and monitoring. Amantadine, a once-daily
oral NMDA antagonist, provides a convenient outpatient antihyperalgesic benefit. Gabapentin, a calcium-channel blocker, possesses
broad analgesic benefits for many types of pain. Combinations of any or all of these medications can be customized to a patient's
needs.
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