Acute perioperative, traumatic, and disease-related (eg, cancer, pancreatitis, pleuritis, otitis externa) pain is generally treated pharmacologically with one or more analgesics. The optimal drug or drug combinations are determined principally by the anticipated severity of pain, health status, and available drugs for the given species. The more extensive the tissue trauma or disease-induced tissue damage is, the greater the need to use analgesics from more than one drug class (multimodal or balanced analgesia). Multimodal analgesia maximizes the beneficial analgesic effects of multiple drugs through additive or synergistic interactions while minimizing adverse drug effects by lowering the dose of any individual drug.
A perioperative approach to managing surgically induced pain should be used, beginning with the administration of an analgesic before surgery (preemptive analgesia) and continuing with appropriate analgesia throughout the intraoperative period. Three days is a useful guideline for the duration of analgesic therapy after acute surgical pain. Depending on multiple factors (eg, procedure performed, rehabilitation plan, species, breed), some animals require a shorter duration of therapy, whereas other animals require analgesia for longer periods. Aggressive analgesic therapy of several days’ duration should be tapered rather than stopped abruptly. As-needed dosing schedules are less effective than scheduled analgesic dosing to treat pain. As-needed protocols require the animal to demonstrate overt pain behaviors to the extent they are recognized by the veterinarian and/or owner. Aggressive prevention and management of acute pain often prevents wind-up of the nociceptive pathways, hastens return to normal function, and decreases the risk of development of chronic pain syndromes.
Minimizing stress and ensuring that overall care and husbandry are in accordance with the needs of the animal improve pain management. Proper housing conditions, nutritional support, and interaction with other animals and/or people should be optimal for the given species and breed. For example, separating a sheep from the flock for pain management may be quite stressful, whereas separating a companion animal from other animals may not be stressful, provided there is sufficient interaction with human caregivers.
Appropriate analgesia after surgery or trauma allows animals to rest. For example, dogs and cats often sleep but should be arousable after surgery if their pain is controlled. The use of pain as a means of restraint (ie, to prevent the animal from injuring a surgical site) is inappropriate; many efficacious chemical and physical restraint modalities are available.
Managing painful and distressed animals requires a combination of good nursing care, nonpharmacologic methods (eg, bandaging, ice packs or heat, physical therapy), and pharmacologic methods. Pharmacologic methods available for the treatment of acute pain may include opioids, NSAIDs, corticosteroids, local anesthetics, α2-agonists, and N-methyl-D-aspartate (NMDA) receptor antagonists such as ketamine. Many animals benefit from the management of anxiety. Acepromazine is an effective anxiolytic in small animals but should be used only after appropriate analgesics have been administered. Acepromazine does not have analgesic properties and is not reversible.