Detecting animal pain is critical if refinement is to be successfully implemented when using animals in science.
Species and individual responses to pain are variable; therefore, it is essential that veterinary staff evaluating animals for pain understand typical species responses and individual behaviours. This includes recognizing changes in the normal behaviour and appearance of the animal.
Diagnosis of pain in animals is seldom made on the basis of a single observation or laboratory value. It is subjective and dependent on a combination of a clinical examination; familiarity with species, breed, and individual behaviour; knowledge of the degree of pain associated with particular procedures or illnesses; and recognition of the signs of discomfort and pain.
Clinical Signs of Pain
Clinical signs (observable without handling the animal) that may indicate pain in terrestrial species include:
- changes in personality or attitude
- abnormal vocalization, especially when a painful area is palpated or the animal is forced to move
- licking, biting, scratching or shaking of a painful area
- changes in the appearance of the coat
- changes in posture or ambulation
- changes in activity level
- changes in appetite, such as a decrease in food and water consumption, leading to weight loss and dehydration
- changes in facial expression
- excessive sweating or salivation
- ocular or nasal discharge
- teeth grinding
- changes in bowel movements or urination
Other clinical signs, requiring the animal to be handled, that may indicate pain include: increases in heart rate, respiratory rate and body temperature, and elevations in blood glucose, corticosteroid and catecholamine concentrations.
Regardless of the clinical signs demonstrated, if there is any doubt that an animal may be experiencing pain, then a trial treatment with analgesics should be initiated.
Minimize this section
Fish have the potential to experience pain, and manipulations that provoke stress or avoidance/escape behaviour may be causes of distress. Fish respond to noxious stimuli (stimuli that are damaging or potentially damaging to normal tissue, such as mechanical pressure, extremes of temperature and corrosive chemicals) with altered behavioural, physiological and hormonal parameters.
Many fish species are prey animals and are genetically predisposed not to exhibit signs of injury or pain, therefore the recognition and evaluation of pain in fish is not simple.
Clinical signs of pain in fish include:
- changes in eye condition, fin and skin condition, mucus production, and/or colour;
- changes in feed consumption
- changes in feeding activity
- changes in respiratory rate
- changes in the individual's position in the water (upright, upside down, tilted, etc.)
- changes in social interactions, such as direct attacks, domination of choice tank locations, schooling, and social isolation
- lack of response to external stimulation
- hyperactivity or hypoactivity
- abnormal movements such as flashing or scraping the body
- unexpected jumping or escape behaviour
- avoidance reaction to mechanical prod or light beam
Other signs that are indicators of acute stress and that may be indicative of pain include changes in corticosteroid and catecholamine levels, as well as increases in plasma glucose and lactic acid.
Regardless of the clinical signs demonstrated, if there is any doubt that a fish may be experiencing pain, then a trial treatment with analgesics should be initiated.
Minimize this section
This section was adapted from the ACVA position paper on the treatment of pain in animals and the CCAC guidelines on: the care and use of fish in research, teaching and testing.
For more information on pain assessment, the following resources may be useful.
CCAC resources
Online articles
Online resources
Reference list organized by species
Other publications
- Flecknell P. and Waterman-Pearson A. (2000) Pain Management in Animals . 180pp London UK: W.B. Saunders.
- Kohn D.F., Martin T.E., Foley P.L., Morris T.H., Swindle M.M., Vogler G.A. and Wixson S.K. (2007) Guidelines for the assessment and management of pain in rodents and rabbits. Journal of the American Association for Laboratory Animal Science (JAALAS) 46(2):97-108.
Minimize this section
