Science of Nociception
Nociception, the process that leads to the conscious perception of pain, has been called the alarm system that announces the presence of a potentially damaging noxious stimulus, such as heat, cold, intense mechanical force, or a chemical irritant.2 The nociceptive system serves a valuable protective function to prevent tissue damage, destruction of joints, loss of digits or appendages, and pressure ulcers. Nociceptive pain is a vital physiologic sensation for preservation of health and prevention of injury, a concept exemplified by the repeated injuries, often leading to a reduced life expectancy, in people with congenital insensitivity to pain.6 While the ability to feel pain is important to one’s health, so too is the need to alleviate extreme or chronic pain. The nociceptive system can be broken down into 4 steps: transduction, transmission, modulation, and perception (Figure 1).6,7 An individual animal’s response to pain varies with many factors, including age, sex, health status, species, and interspecies variation.8
2. Ray AL. Neuroplasticity, sensitization, and pain. In: Deer TR, Leong MS, Ray AL, eds. Treatment of Chronic Pain by Integrative Approaches: The American Academy of Pain Medicine Textbook on Pain Management. New York, NY: Springer Science+Business Media; 2015:15-24.
6. Woolf CJ, American College of Physicians, American Physiological Society. Pain: moving from symptom control toward mechanism-specific pharmacologic management. Ann Intern Med. 2004;140(6):444-451.
7. Beckman B. Anesthesia and pain management for small animals. Vet Clin. 2013;43(3):669-688.
8. American College of Veterinary Anesthesiologists’ position paper on the treatment of pain in animals. http://www.acvaa.org/docs/Pain_Treatment. Updated 2006. Accessed July 22, 2016.