Pain serves a protective role that alerts an individual to injury from the environment or from within. For example, if a muscle strain or pull causes pain in a limb, not putting weight on that limb can help prevent further injury.
The most common types of pain can be categorized as acute, chronic, cancer, and neuropathic.
Acute pain is the normal, predictable, noticeable response to an undesirable stimulus (such as twisting, crushing, or burning) or tissue injury (such as bruises, wounds, and surgical incisions). People describe acute pain as sharp, throbbing, aching, or burning. Acute pain generally improves within the first 3 days after the event that caused it but can last through the time of healing (up to 3 months).
Chronic pain persists for longer than the expected time frame for healing, or it can be associated with progressive noncancerous disease, such as osteoarthritis.
Cancer pain may have components of both acute pain (due to primary tumor growth, a spreading cancerous disease, or the toxic effects of chemotherapy or radiation) and chronic pain.
Neuropathic pain results from damage to a nerve or some other part of the central nervous system. This type of pain is not frequently diagnosed in veterinary medicine, mainly because animals cannot communicate a problem such as a tingling sensation.