Lecture 6 Assessing Pain in Animals

Behavioural Methods for Assessing Pain in Animals

Key Concepts

• Animal Welfare

  • Definition: The overall state within an animal, based on its mental and physical experiences.

  • Interpretation of experiences involves:

  • Physical state (biological function)

  • Interactions with the environment

  • Expression of motivated behaviors

  • Positive experiences enhance welfare, while negative ones diminish it.

• Five Domains Model for Welfare Evaluation

  1. Nutrition/Hydration

  • Assess the quality, variety, and volume of food/water intake.

  1. Environment

  • Consider conditions such as thermal extremes, air quality, and noise.

  1. Health/Functional Status

  • Include the presence of disease, injury, and overall physical fitness.

  1. Behaviour

  • Observe for restrictions and opportunities for natural behavior.

  1. Mental Experiences

  • Identify mental states such as fear, anxiety, and malaise.

Differentiating Nociception from Pain

• Nociception: The sensory process of detecting pain signals due to tissue damage.

• Pain: An emotional experience linked to nociception indicating awareness of damage, affecting behaviour and physiology to promote recovery.

Behavioural Assessment of Pain

Methods to assess pain in animals through observed behaviors:

1. Quantitative (Spontaneous) Behaviour Assessment

2. Learned Avoidance

3. Motivational Trade-offs

4. Effects of Analgesia

5. Nociceptive Threshold Testing

6. Facial Expressions

7. Gait Analysis

8. Visual Analogue Scales

9. Pain Scales

10. Qualitative Behavioural Assessment

Factors Affecting Behavioural Expression of Pain

• Variability based on:

  • Species

  • Breed

  • Age

  • Sex

  • Severity and duration of tissue damage

  • Individual characteristics (baseline sensitivity, prior experience)

Pain Experience in Animals

• Case Study: Hermit crabs (Pagurus bernhardus) showed motivational trade-offs when given electric shocks.

  • Indication of pain inferred from behavior changes regarding shell abandonment.

Conclusion

• Understanding animal welfare requires careful interpretation of behavior to infer emotional and physical states.

• Each method for assessing pain provides insights into the welfare state of the animal.