Merck Manual

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Pet Owner Version

Types of Pain


Sandra Allweiler

, DVM, DACVAA, Department of Clinical Sciences, Carlson College of Veterinary Medicine, Oregon State University

Reviewed/Revised Feb 2020 | Modified Nov 2022
Topic Resources

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.

Signs of Pain in Pets

You can play a central role in relieving your pet’s pain by learning to recognize some common indicators of pain and discomfort.

Physical Signs

  • Change in heart rate

  • Change in breathing pattern

  • Change in movement or posture

  • Slowed reflexes

Behavioral Signs

  • Reduced appetite

  • Reluctance to move or difficulty getting comfortable

  • Unusual restlessness or anxiety

  • Withdrawn behavior

  • Mood or personality changes

  • Licking, biting, or rubbing the site of pain

  • Irritability

Modified with permission from Colorado State University Animal Cancer Center website, “How will I know if my pet is in pain?

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.

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