Pain and analgesia
Ratification Date: 04 Dec 2014
Pain in animals must be prevented, relieved and managed whenever possible. Euthanasia is indicated where an animal is suffering, or is likely to suffer, intractable pain, where treatment is ineffective or is not pursued.
Preventing and managing physical and mental pain is a fundamental part of patient care in veterinary medicine. Treatment programs should always be designed to alleviate or manage pain wherever possible after the cause of the pain has been diagnosed.
There is sound scientific evidence that animals feel pain.1 It is well established that animals and humans have similar neural pathways for the development, conduction and modulation of pain.2 Injuries, disease conditions and many procedures may cause pain in animals. Signs and treatments may vary according to species.3,4,5
Pain is understood to have survival value. Where analgesics are unavailable (as in the wild), acute pain can change behaviour and prevent further damage, but if pain is unrelieved, it can lead to destructive behaviour and suffering. Pain can induce physiological changes that may be detrimental to patients including increased sympathetic tone, reduced gastrointestinal and urinary blood flow, increased blood viscosity, prolongation of clotting times and altered platelet aggregation. In the long term there is increased risk of thromboembolic disease, ventilation: perfusion mismatch, hypercapnia, hypoxaemia, increased myocardial workload and oxygen consumption, immunosuppression and delayed wound healing.6
Unless there is evidence to the contrary, it must be assumed that procedures and conditions that would cause pain and distress in humans cause pain and distress in animals. Because pain cannot be directly measured in animals, veterinarians rely on physiological measurements and behavioural observations for indirect evidence of pain in animals.
Acute pain results from a traumatic, surgical, or disease processes, that is abrupt in onset and relatively short in duration. The pain generally does not outlast the healing process; it can generally be alleviated by analgesics.
Chronic pain results from long-standing physical disorders or emotional distress; it is usually slow in onset and has a long duration. Chronic pain is often more difficult to treat than acute pain and may require extensive diagnostic investigation and multiple therapeutic approaches. Pain can also be classified as adaptive or maladaptive. Adaptive pain is a normal response to tissue damage, such as pain associated with inflammation. If adaptive pain is not appropriately managed, physical changes can occur in the spinal cord and brain and it becomes maladaptive. Examples include neuropathic or central pain.
Veterinarians should observe and monitor animals in their care for signs of pain. If an animal is suffering pain, or painful procedures are to be carried out, the veterinarian responsible for its care should recommend or use evidence-based methods — including drugs, behavioural and physical therapy — to relieve pain and ensure the effectiveness of the pain relief and quality of life.
Therapeutic strategies should be aimed at improving an animal’s ability to cope with pain, thereby decreasing suffering. Complete alleviation of an animal’s pain may not be achievable. Treatment of pain can be considered successful if the animal is able to engage in relatively normal activities, such as eating, sleeping, ambulating, grooming and interacting with other members of its species or its care-givers.
Other relevant policies and position statements
- Le Bars D, Gozariu M and Cadden SW (2001). Animal models of nociception. Pharmacol Rev 53(4):597–652.
- Hellyer P, Rodan I, Brunt J, Downing R, Hagedorn JE, Robertson SA (2007). AAHA/AAFP Pain management Guidelines for Dogs and Cats. J Am Anim Hosp Assoc 43: 235-248.
- Landa, L (2012). Pain in domestic animals and how to assess it: a review. Veterinární Medicína, Vol. 57 Issue 4, p185-192.
- Valverde A and Gunkel C (2005). Pain management in horses and farm animals. Journal of Veterinary Emergency & Critical Care. Dec 2005, Vol. 15 Issue 4, p295-307
- Hunt, J (2014). Pain assessment in small animal practice. Companion Animal, Vol. 19 Issue 3, p125-129
- Looney A (2009), Acute Pain Management. In Bonagura JD and Twedt DC (eds). Kirk’s Current Veterinary Therapy, 14th edition St Louis, Missouri: Elsevier Saunders: 9-17.
Date of ratification by AVA Board: 4 December 2014