Measuring Pain

Pain = An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage

False We don’t need potential tissue damage to feel pain

It’s an individual experience It has a protective function

First in the pain pathway is a pain inducing stimulus The pain receptors then activate and translate and transmit signals through C and A-Delta fibres The signal travels through the C and A-Delta fibres to the Peripheral Central Nervous Systems spinal cord This triggers a reflex to move the body part away from the pain inducing stimulus The pain signal will then continue up to the brains thalamus to feel the pain

Animal pain = “ An aversive sensory and emotional experience representing an awareness by the animal of damage or threat to the integrity of its tissues It changes the animals physiology and behaviours to reduce or avoid damage, to reduce the likelihood of recurrence and to promote recovery”

1) Nociceptive 2) Neuropathic 3) Acute pain 4) Chronic pain

Nociceptive pain is acute sharp pain Nociceptive pain responds to the following stimuli: - Thermal - Mechanical - Chemical You can get superficial somatic vs deep somatic vs visceral

Neuropathic pain is where damaged and/or sensitised nerves fire in the absence of tissue damage

Acute pain has relatively short duration of pain It has an obvious cause It resolves with healing It has a protective function

Chronic pain could have multiple causes Chronic pain persists after healing It’s often refractory to treatment

First there’s inflammation, tissue injury and nerve damage which leads to pain The following systems will then activate: - Neuroendocrine systems changes - Sympathoadrenal activation - Neuroplasticity (spinal cord and CNS) - Inflammatory mediators “sensitising soup” - Central processing changes Activation of all these systems leads to infection and impaired wound healing

Neuroplasticity is changes in the somatosensory system which will generate central sensitisation and facilitated CNS transmission The firing of these neurones then causes hyperalgesia and allodynia

True

Hyperalgesia Allodynia

Hyperalgesia = “An increased response to a stimulus which is normally painful”

Allodynia = Pain due to a stimulus which does not normally provoke pain

Physiological indicators Behavioural indicators Pain scales/questionnaire Threshold test and cognitive bias Neurological indicators

Tachycardia, hypertension and cardiac arrhythmia Pale mucous membrane Mydriasis Sweating, trembling, hypersalivation Increased urination or defication Poor body or coat condition Changes in stress hormones such as: Cortisol Glucose Insulin Adrenaline Endorphins

They're unreliable and non-specific if taken as a sole parameter We need knowledge about physiology of the species evaluated to know what's normal Errors are increased with Disease Fear Stress Handling Anaesthesia Etc

True

True

False Behavioural indicators vary within species

True

Abnormal posture Abnormal activity Abnormal movement Abnormal gait Reluctance to move Depression, inappetence, dullness Manic behaviour Not grooming Trembling Poor interaction with people, hiding Non-interested in surroundings Decreased interactions with other animals Tooth grinding Poor cognition Ear-flicks Aggression Paying attention to the injured area or wound, hyperalgesia when palpated Vocalisation Whining, crying, howling Head hanging down, low tail carriage