Pain and analgesia

Question 1

What is the definition of pain?

Answer 1

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

Question 2

What is adaptive and maladaptive pain?

Answer 2

Adaptive pain is protective, e.g. nociceptive pain or inflammatory pain
Maladaptive pain has no protective function, e.g. neuropathic pain

Question 3

What is the definition of chronic pain?

Answer 3

Pain lasting longer than a month with a wide range of often subtle behavioral changes

Question 4

What are the three processes in pain?

Answer 4

Nociception (sensory process by which a noxious stimulus is transmitted to the brain)
Perception (of noxious stimulus in the CNS
Behavioural response to pain (varies according to species) - important in assessing pain

Question 5

What is hyperalgesia?

Answer 5

Pain sensitivity increases if noxious stimuli experienced repeatedly in a certain time period. Takes time after noxious even for pain sensitivity to return to the baseline. It will be elevated for a while

Question 6

What are the implications of hyperalgesia in a clinical context?

Answer 6

Pain will be more severe
Analgesic drugs may be less effective if given once pain is present already
One type of analgesic drug may no longer be sufficient

Question 7

How do we assess pain in animals?

Answer 7

Pain scoring systems available. Look at things like demeanour in kennel, response to exercise, behaviour, body language etc.
Want to be repeatable, simple, objjective

Question 8

What are the two decent pain assessment systems in horses?

Answer 8

Composite orthopaedic pain scale (COPS)

Post Abdominal Surgery Pain Assessment Scale (PASPAS)

Question 9

What is pre emptive analgesia?

Answer 9

Administration of analgesia drugs before the onset of noxious events (included in permed)

Question 10

What are the benefits of using multi modal analgesia?

Answer 10

Better pain relief achieved, allows lower doses of each individual drug-reduces side effects

Question 11

What are the 7 available systemic analgesia drugs/classes?

Oh No Kelly! Look At That Giraffe

Answer 11

Opioids, NSAIDs, Ketamine, Lidocaine, a2 agonists, tramadol, Gabapentin

Question 12

What are the three classes.drugs used for local analgesia?

Answer 12

Local anaesthetics,
opioids
alpha-2s

Question 13

What is an opioid?

Answer 13

Any product natural or synthetic that binds to the opioid receptors and shares the properties of the naturall occuring endogenous opioids

Question 14

What is an opiate?

Answer 14

Any naturally occuring opioid derived from opium (e.g. morphine, codeine)

Question 15

What are the naturally occuring opioids?

Answer 15

Morphine & codeine

Question 16

What are the semi-synthetic opioids?

Answer 16

Dihydromorphine, Diamorphine (heroin), hydro-morphine & Buprenorphine

Question 17

What are the synthetic opioids?

Answer 17

Pethedine 
Methadone
Fentanyl
Butorphanol
Tramadol
(PethMethFenButTram)

Question 18

What are the effects mediated by the delta opioid receptor?

Answer 18

Spinal and supraspinal analgesia

Reduced gastric motility

Question 19

What are the effects mediated by the kappa opioid receptor?

Answer 19

Spinal analgesia
Diuresis
Dysphoria

Question 20

What are the effects of the miu opioid receptor?

Answer 20

Sedation, analgesia, bradycardia, respiratory depression

Question 21

What are the effects of NOP receptors?

Answer 21

Spinal analgesia

Question 22

What receptor do morphine, pethidine, methadone, fentanyl and buprenorphine all work at?

Answer 22

miu receptor

All are full agonists except buprenorphone which is partial

Question 23

What receptor(s) does butorphanol work at?

Answer 23

agonist at kappa, antagonist at miu

Question 24

What are the two opioid antagonist drugs?

Answer 24

Naloxone

Diprenorphine (revivon)

Question 25

Why should buprenorphine only be used for mild-moderate pain?

Answer 25

It is only a partial agonist of the miu receptor, cannot produce maximal effect

Question 26

Which opioid can you not give IV?

Answer 26

Pethidine

Question 27

Which species do opioids cause CNS depression in?

Answer 27

Dogs, monkeys and people | --> sedation

Question 28

Which species do opioids cause CNS stimulation in?

Answer 28

cats, horses, ruminants | --> euphoria and dysphoria

Question 29

What are the common side effects of opioids?

Answer 29

Vomiting and nausea due to stimulation of the CTZ (dogs mainly) - rarely if pain present Variation in pupil size due to stimulation of oculomotor nuclei, NB not seen in cats as counteracted by circulating catecholamines Thermoregulation - decrease in set point in dogs, panting seen. Can cause hyperthermia in cats, horses, pigs and ruminants due to increased muscle activity Respiratory depression - miu mediated effect on respiratory centre, due to decreased responsiveness to CO2 Bradycardia-Vagal stimulation, responsive to anticholinergics. Pethidine is an exception

Question 30

Which of the opioids does not cause bradycardia?

Answer 30

Pethidine

Question 31

Pure agonists are schedule 2 controlled drugs and therefore..

Answer 31

Must be kept in a locked cupboard Must be recorded when they are purchased and used Must have a special prescription Must be dosposed of according to legislation

Question 32

Buprenorphine (partial agonist) is a schedule 3 drug and therefore..

Answer 32

Should be kept in a locked cupboard but no record of use necessary

Question 33

Which opioid is currently exempt from legislation restrictions?

Answer 33

Butorphanol | probably why all the horse people like it so much!

Question 34

What receptor does Ketamine block?

Answer 34

NMDA receptor

Question 35

What are the indications for use of ketamine?

Answer 35

Skin surgeries including grafts and burns | Neurogenic pain e.g. amputation