A narrative review on canine chronic pain: neurobiological insights and assessment methods to establish quality of life

Chronic or maladaptive pain is a frequent condition in canine patients that causes alterations due to the persistent sensitization of pain receptors. Among these alterations are changes in the animal’s behavior, posture modifications, temperament, vocalization, and/or reduced movement. Thus, chronic pain affects the behavior and physiology of animals, reducing their welfare and quality of life. This narrative review aims to analyze the physiopathology of chronic or maladaptive pain, describing behavioral changes, its association with quality of life, and evaluation methods to assess chronic pain. Currently, different chronic pain scales categorize the level of discomfort and can evaluate the effectiveness of the treatment. These tools rely on surveys evaluating pain severity and its consequences on daily activities or functional limitations. Chronic pain scales can guide both veterinarians and owners about how the animal’s quality of life has deteriorated when considering certain painful diseases. However, the application of these scales is limited –when compared to acute pain scales– and some of them require training to accurately evaluate chronic pain and its management.