Position Statements

Pain Management in Animals (Previously Pain Control in Animals)

February 22, 2022

Position

The Canadian Veterinary Medical Association (CVMA) holds that veterinarians have a duty to use appropriate pain management protocols for surgical procedures and for the treatment of medical conditions that result in or are likely to cause pain.

Summary

  • Animal pain and suffering are clinically important conditions that adversely affect health and quality of life.
  • The veterinary profession must apply the precautionary principle regarding an animal’s ability to experience pain and make recommendations regarding pain prevention and management accordingly.
  • The potential for pain in animals resulting from surgical procedures or medical conditions must always be considered, and pain must be prevented or treated as effectively as possible.
  • Veterinarians have the required knowledge and skill to prevent, eliminate, reduce, or mitigate pain.
  • Veterinarians must stay current in the recognition and management of pain in the species they treat.

Background

  1. Pain is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage” (1).
  2. Nociception is “a sensory ability to respond to damaging stimuli”. It is present in many species and can occur without an animal feeling pain.
  3. Many animals show physiological and behavioural responses to nociception similar to those that occur when humans experience pain. There is a lack of definitive evidence to determine the extent to which animals can experience pain; therefore, the ‘precautionary principle’ should be applied where the evidence leads to uncertainty (2). As a result, the veterinary profession must make recommendations regarding pain prevention and management as if all animals in their care are capable of experiencing pain.
  4. Pain and suffering are clinically important conditions that adversely affect an animal's health and quality of life, either in the short or long term (3).
  5. Veterinarians have a professional responsibility to be able to recognize pain and distress in multiple species and to stay current with new developments in pain prevention, recognition, and management (4,5). Species-typical responses to pain are increasingly well-described and the capacity of animals to experience pain should not be dismissed due to pain masking behaviour (6-19).
  6. Acute pain varies in severity from mild to severe, and can be induced by trauma, surgery, or disease. The intensity of acute pain following a tissue insult is usually greatest within the first 24 to 72 hours and frequently responds favorably to analgesic drugs (20).
  7. Chronic pain lasts from months to years and is pain that persists beyond the time usually required for an injury to heal and is associated with a chronic pathologic process.  It often requires long term administration of medication[s] as well as the modification of the animal’s environment, body condition, activity levels, and functional usage. Chronic pain may also respond favorably to non-pharmacological interventions (20).
  8. Neuropathic pain is chronic and originates from injury of the peripheral or central nervous systems.  Different causes include trauma (e.g., amputation and crushing injury), vascular injury (e.g., thromboembolic disease), endocrinopathy (e.g., diabetes mellitus), or infection (e.g., post-herpetic neuralgia) (21). Neuropathic pain often requires several classes of medications as it often cannot be adequately managed with a single pharmacological therapy (20).
  9. Successful management of surgical pain requires thoughtful planning of peri-operative analgesia to ensure effective pain relief is provided before, during, and after surgery. A multi-modal regimen may be required for higher intensity pain as a single class of analgesic may be inadequate. Sedation may be required to ensure stress and fear are minimised. While sedatives (e.g., phenothiazines, benzodiazepines) and general anesthetics (e.g., thiopental, propofol, inhalants) alter the perception of pain, they do not substantially alter nociceptive processing and should not be considered analgesic drugs (22, 23).
  10. The concurrent use of two or more pharmacologic classes of analgesic drugs (opioids, alpha-2 agonists, anti-inflammatories, local and regional anesthetics, dissociative anesthetics, and GABA analogues) generally provides more effective pain control, with fewer side-effects, than therapy with a single drug (24, 25). The potential for adverse side effects, which can occur when higher doses of a single agent are used, is also reduced (26, 27).
  11. Non-pharmacological pain management interventions should be implemented in addition to pharmacological interventions as part of a holistic pain management approach. These may include but are not limited to: environmental modification (e.g. access to conspecifics, quiet resting areas), rehabilitation therapy, manipulative medicine, cryotherapy, thermotherapy, acupuncture, therapeutic ultrasound and laser therapy.   The use of complementary and alternative medicine for pain control is considered in the CVMA Position Statement on Complementary and Alternative Veterinary Medicine (28).
  12. Currently, some anesthetic and analgesic drugs are licensed for use in companion animals, but fewer are licensed for use in livestock, research, or wild animals. The CVMA recognizes that there is an urgent need to approve anesthetic and analgesic drugs for food animal species, and to provide veterinarians and producers with appropriate withdrawal times for these drugs.  
  13. The CVMA supports quality assurance programs that promote humane treatment of all species through the prudent use of extra-label anesthetic and analgesic drugs. Given the current lack of anesthetic and analgesic drugs licensed for use in livestock and wild animals, the CVMA supports the responsible extra-label use of these drugs by veterinarians (29).  Additional information can be found on the CVMA Position Statement on Extra-label Drug Use (30). The CVMA also urges federal regulators to develop programs that facilitate approval of species-appropriate anesthetic and analgesic drugs, or to exempt most of these drugs from restrictions that unintentionally result in unnecessary animal pain.
  14. The CVMA holds that economic considerations, such as the costs of providing analgesic drugs, training personnel and extra handling must not influence the use of pain control for surgical procedures undertaken by producers and caretakers.
  15. The CVMA encourages veterinarians to (a) ensure that their clients or researchers who engage in approved potentially painful procedures on animals are fully trained in best techniques, how to provide pain control, and how to recognize acute and chronic pain; and (b) make appropriate pain control drugs available for their clients to use when clients are undertaking painful procedures (31).

 

References

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  18. K.Reijgwart, M. L. et al. The composition and initial evaluation of a grimace scale in ferrets after surgical implantation of a telemetry probe. PLoS One 12 (2017). Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0187986. Last accessed September 2021.
  19. L.Holden, E. et al. Evaluation of facial expression in acute pain in cats. J. Small Anim. Pract. 55, 615–621 (2014).
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  28. CVMA Position Statement on Complementary and Alternative Medicine (2019). Available from: https://www.canadianveterinarians.net/documents/complementary-alternative-veterinary-med icine-october-2019. Last accessed September 2021.
  29. Smith G.  Extralabel use of anesthetic and analgesic compounds in cattle. Vet Clin North Am Food Anim Pract 2013;29:29-45.
  30. CVMA Position Statement on Extra-Label Drug Use. Available from: CVMA | Documents | Off-Label Use of Drugs (UMDDE) – Position Statement (veterinairesaucanada.net) Last accessed September 2021.
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