34 – Exotic Pet Analgesia

Question 1

Overall what is important about small animals metabolic rates?

Answer 1

• FASTER metabolic rate

Question 2

Prey species: pain recognition

Answer 2

• Most HIDE signs of sickness or pain
• May pretend to eat/groom in stressful situations
• *Difficult to assess pain
• Observer bias can make studies different

Question 3

Recognizing pain in small mammals

Answer 3

• Mostly prey species
• Body position/posture
• Activity and attitude changes
• Unkempt hair coat
• Appetite and fecal production
• Facial expression: grimace scale

Question 4

Rat grimace scale: components

Answer 4

• Orbital tightening
• Nose/cheek flattening: absence of crease b/w cheek and whisker pads
• Ear changes=pointed shape
  o Some rats have ears naturally to the sides (genetic selection)
• Whisker change: move forward away from face
  o Ferrets: if go back=pain (DIFFERENCE!)

Question 5

‘blood’ stain around the eyes

Answer 5

• NOT BLOOD
• Pigment released from lacrimal gland (goes in urine of rabbits)
• *NON-SPECIFIC: stress, overcrowding, illness, just not doing well

Question 6

Rabbits analgesia: info

Answer 6

• Many drugs tested on them, but info difficult to find
• Studies on young, healthy animals
• Shorter time frames
• Small number of animals
• Studies NOT usually looking at analgesia (often looking at toxic effects, PK)

Question 7

Ferrets and opioids

Answer 7

• LOWER dosages compared to other small mammals (similar to cats: ‘little cat’)
• Buprenorphine: SQ not great (like cats)
  o IM or IV
• Predator

Question 8

Guinea pigs and chinchillas: opioids

Answer 8

• Dosages for analgesia are 10x those of a cat!

Question 9

Opioids: variety of routes available

Answer 9

• IM, SC for sedation
• IV, IM, SC for hospitalized patients
• Oral transmucosal (OTM): limited absorption, but can be administered more often
  o Herbivore: more keratinized mucosa=don’t go through as well, so give higher dosages (10x the dose, some going orally, but wont do anything)
  o Difficult for most people to do AT HOME
  o *expensive (buprenorphine)

Question 10

Tramadol studies (opioids)

Answer 10

• Not analgesic in chinchillas and can get neurological signs
• Rabbits maybe at higher doses but not reliable
• *limited at home use

Question 11

Hydromorphone in chinchilla

Answer 11

• Analgesia at a minimum (2mg/kg) and slows GI transit

Question 12

NSAID: analgesia

Answer 12

• *Meloxicam is most commonly used
• Ferrets more similar to small animals patients (dogs and cats)
• Lacking studies

Question 13

*NSAIDs in rabbits

Answer 13

• Tolerated well (can’t vomit)
  o Tastes good=take it well
• No drug accumulation or toxicosis in liver, urinary bladder, GIT, kidneys
• *limited: only young, healthy rabbits
• *give 1mg/kg (5x higher) and give twice daily!

Question 14

Lidocaine analgesia

Answer 14

• Can be administrated CRI, alone or with other agents
• CRI demonstrated to provide better analgesia than buprenorphine
• *good for VISCERAL PAIN
• Lidocaine and bupivacaine used for local blocks and epidural

Question 15

Analgesia protocol:

Answer 15

• Choose opioid base on estimated intensity of pain
  o Buprenorphine has plateau effect: MODERATE
  o Hydromorphone, morphine or fentanyl: INTENSE
• *opioid + NSAID
• *opioid + lidocaine CRI in rabbits

Question 16

Avian ‘differences’

Answer 16

• KIDNEYS
• *Fast metabolism (especially psittacine): high body temperature
  o Need higher doses
• Mostly done on poultry: does NOT work to compare to parrots

Question 17

Pain recognition in birds

Answer 17

• *Squinty eyes: ‘I am unwell’
• Laying low, hunched
• Fluffed feathers (puffier): unless a baby bird

Question 18

Avian analgesia: opioid receptors?

Answer 18

• DIFFERENCES between avian orders!
• Most psittacine evaluated: Hispaniolan Amazon Parrot (HAP)
• *thought that they had more kappa receptors: use butorphanol
  o NOT true across the board!

Question 19

Opioids in psittacine (parrots, buggies, etc.)

Answer 19

• Butorphonal: opioid of choice
• Tramadole
  o If give lots=can produce analgesia, give every 8 hrs (oral administration)

Question 20

Butorphanol in psittacines

Answer 20

• More Kappa receptors
• Short half-life, need to re-dose often!
  o Challenge
• Can do CRI
• Liposome encapsulated formulation in but not commercially available

Question 21

Opioids in raptors

Answer 21

• Mu receptors more represented
• Majority of research on kestrels (falcons)
  o May be different for other raptor species
• *hydromorphone (buprenorphine doesn’t work great)
  o Effective at range of dosages
  o Significant sedation at high disease
  o Dose every 3-6 hours
• Butorphanol=considered ineffective

Question 22

Buprenorphine in raptors

Answer 22

• Similar to hydromorphone
• Does not sedate as much
• Sex differences

Question 23

Tramadol in raptors

Answer 23

• Small raptors: higher PK=higher doses

Question 24

NSAIDs in psittacines

Answer 24

• High metabolism=higher dosages
• *meloxicam
  o Twice daily
  o Well tolerated (not many hepatic or renal effects)
• Flunixin-meglumine: does not work well

Question 25

NSAIDs in raptors

Answer 25

• No PK or PD studies
• Diclofenac=TOXIC
• Carprofen, flunixin, phenylbutazone=toxic, but not as lethal
• *restrict it to meloxicam=safe

Question 26

Reptiles metabolism

Answer 26

• Slow metabolism
  o Lower dosages
  o Longer duration
  o Slower absorption
• *depends on environment

Question 27

Reptiles pain or no pain?

Answer 27

• YES, just don’t show you
  o *not dramatic
• *if you think painful to human=probably painful in reptile

Question 28

Evidence for pain perception in reptiles

Answer 28

• Behavioural response to painful stimuli
• ID of pain pathways
• Demonstration of effective analgesia

Question 29

Signs of pain in reptiles

Answer 29

• May not be observed
• Aggression in predators species
• Chelonians: stretch neck, close eyes, bite
• Snakes: restless (MORE ACTIVE), easily startled, agitated, less coiled, tuck away painful area
• Lizards: postural changes, flicking at area

Question 30

Reptiles: opioids

Answer 30

• Some mu and some kappa (difficult to extrapolate)
• Hard to assess sedative effect
• Varying absorption when drug administered in pelvic limbs

Question 31

Chelonians and opioids

Answer 31

• Mu agonists provide the best analgesia
• Morphine: higher dose than mammals
  o Monitor side effects
• Hydromorphone superior to buprenorphine in red-eared sliders
• Tramadol provides analgesia with minimal respiratory depression

Question 32

Lizards and opioids

Answer 32

• Pure mu-agonists
• Butorphanol not great
• Morphine can work

Question 33

Snakes and opioids

Answer 33

• Differ from lizards and chelonians
• Corn snakes: butorphanol superior to morphine
• Fentanyl patches tested: high plasma concentration, but no change in thermal nociception

Question 34

Reptiles: NSAIDs

Answer 34

• *meloxicam
• Low dosages and frequencies due to slower metabolism
• Limited PK and PD studies