Pain management for dogs and cats by Brian Daubs.

1. Lets talk about Pain
Brian Daubs
Surgery Resident
Veterinary Specialists of South Florida
Cooper City, FL

2. Painful??

3. Pathway overview
Painful stimuli causes
 Disruption of phospholipid membrane
Creates inflammation via arachidonic acid cascade
Metabolites of AA cascade activate afferent fibers
 Direct activation of afferent fibers (a-delta and C
fibers)
These afferent nerves synapse in the dorsal
horn of the grey matter
The impulse travels up ascending pathways and
terminate by synapsing in somatosensory cortex

4. Activation of the pain pathway causes
Release of numerous intracellular substances
 Hydrogen, potassium ions, serotonin,
histamine, prostaglandins, bradykinin,
substance P, acetylcholine, and many others.
Bradykinin, potassium, and sP directly activate
nociceptors
Prostaglandins sensitize the nociceptors
facilitating depolarization.

5. Activation of the pain pathway can cause
Increased heart rate, stroke volume, cardiac oxygen
consumption, may cause arrhythmias
Shock
Ileus
Reduced urinary output
Hypo or hyperventilation
Wind up of both peripheral and central nociceptors
Increased release of cortisol, ACTH, Glucagon, cAMP,
ADH, growth hormone, renin, and other catabolically
active hormones
Negative energy balance leading to immunosuppression

6. Arachidonic acid cascade

7. Arachidonic acid cascade

8. NSAIDs mechanism of action
Ketofen (ketoprofen) – cox 1and cox 2 inhibition
Banamine (flunixin meglumine) - cox 1and cox 2
inhibition
Feldene (piroxicam) – unknown probably cox
1and cox 2 inhibition
Rimadyl (carprofen)- cox 2 preferential
Metacam (meloxicam) – cox 2 preferential
Deramaxx (deracoxib)- cox 2 selective
EtoGesic (etodolac) - cox 2 selective
Previcox (firocoxib) - cox 2 selective

10. Nerve blocks and epidural
Local or regional- lidocaine, bupivacaine
or ropivacaine blocks
 Mechanism of action – Na channel blockade
Consider lidocaine patch
Epidural- allows delivery of a μ receptor
agonist, bupivacaine, alpha 2 agonists, or
ketamine.

11. Opioids
μ and k- high concentration in CNS, may be
present outside the CNS
μ agonist- morphine, hydromorphone,
oxymorphone, fentanyl, meperidine, tramadol
Partial μ agonist- buprenorphine has a higher
affinity for the μ receptor than the pure μ
agonists.
μ antagonist- butorphanol and naloxone
k agonist - butorphanol

12. Alpha 2 agonists
Alpha 2 agonists bind to receptors in the
CNS and in other tissues leading to
sedation, peripheral vasoconstriction,
bradycardia, respiratory depression,
diuresis, muscle relaxation
and analgesia.

13. Multimodal pain management
Use a combination of pain medications
with different MOA to treat pain
 This allows a reduced dose for all medication
and less detrimental side effect
5 modalities we can treat pain with are
NSAIDs, the caines, opioids, NMDA
antagonists, and alpha 2’s

14. Wind up or Hyperalgesia
Wind up can occur after one episode of
acute pain or more commonly occurs after
chronic pain.
 Suspect substance P at NK-1 receptors are
involve
 Suspect glutamate at NMDA receptors are
involve.
Best treatment is preemptive analgesia
Gabapentin and ketamine may help

15. Preemptive analgesia
The preventative medicine of pain
Blocking the pain pathways before any
tissue injury will decrease the dose and
frequency of analgesics after tissue injury.
 Also decreases the amount of inhalant
anesthesia needed
 Provides a quicker return to normal function
 Decreases cost to the client

16. CRI, IM, IV
1 2 3 4 5 6 7 8 9 10 11 12
S1
5
4
3
2
1
0
Time
[Drug]

17. Assessing the painful patient
Most reliable indicators are
 Heart rate
 Blood pressure
 Respiratory rate
More subjective parameters are
 Vocalization
 Appearance
 Activity or restlessness
Take em out to pee!

18. Painful ??

19. Prayer position

20. Prayer position

21. Case review
Princess a 4 mo female spayed mix breed
was trapped in a house fire. Stabilized and
treated for smoke inhalation by the
emergency group. No significant burns
were present at that time.
At the first recheck a fluid pocket was
present over her back, penrose drains
were placed
Pain meds: Deramaxx and tramadol

22. Second recheck

23. Princess was hospitalized due to
the progressive burn lesion
Pain management
Day 1 pain management
 oral morphine Gabapentin, and Deramaxx.
Day 2
 Continued oral morphine Gabapentin, Deramaxx and added 3 CRI’s of lidocaine, ketamine,
and domitor
Day 3
 Continued Gabapentin and Deramaxx and added
 fent cri at 5 mcg/kg/hr
 lidocaine cri at 25 mcg/kg/min
 ketamine cri at 2 mcg/ kg/ min
 domitor cri at 1.2 mcg/kg/ hr
Day 7
 Continued Gabapentin and Deramaxx…
 fent cri at 12 mcg/kg/hr
 lidocaine cri at 35 mcg/kg/min
 ketamine cri at 4 mcg/ kg/ min
 domitor cri at 8 mcg/kg/ hr

24. Debridement

25. Hospitalization continued
On day 8
 All the CRI’s were discontinued except a cri
of fentanyl at 4 mcg/kg/hr.
On day 9 discharged to owners for
bandage changes every 3 days for the
next 3 weeks
At home pain meds
 Gabapentin and Deramaxx

26. discharge

27. Pre op

28. Post op

29. Perioperative pain management
Fentanyl CRI, hydromorphone premed
Sent home on tramadol and Deramaxx

30. Recheck

31. Cats
Tend to get a temperature spike after
hydromorphone, fentanyl, and other drugs at
anesthesia, adjust opioid dose based on pupil
size
Tend to handle oxymorphone with less
temperature variation and less dysphoria (no
data to support this)
NSAIDS are fine in young healthy cats use low
end of dose and discontinue after 5 days
Cats are sensitive to the cains, avoid CRI.
Epidurals, local blocks, and chest tube infusions
are fine.

32. NSAID Doses dogs
Ketofen (ketoprofen) – 2mg/kg im/sq once
Feldene (piroxicam) –0.3 mg/kg po sid
Rimadyl (carprofen)-2.2 mg/kg bid or 4.4
mg/kg po sid
Metacam (meloxicam) – 0.1 mg/kg po sid
Deramaxx (deracoxib)-1-2 mg/kg po sid
EtoGesic (etodolac) -10 mg/kg po sid
Previcox (firocoxib) -5 mg/kg po sid

33. CRI doses
Fentanyl -2-10 mcg/kg/hr (up to 45
mcg/kg/hr for anesthesia)
 Load with 3 mcg/kg iv
Morphine 0.12-0.36 mg/kg/hr
 Load with 0.5 mg/kg im
Lidocaine 0.6 3 mg/kg/hr
Ketamine 0.12-1.2 mg/kg/hr
 Load with 0.25 mg/kg

34. CRI doses
Butorphanol 0.04 - 0.1 mg/kg/hr
 Load 0.1 mg/kg
Hydromorphone- 0.01-0.04 mg/kg/hr
 Load 0.02 mg/kg
Medatomidine 1-10 mcg/kg/hr

35. Questions ??

36. References
1. Robinson E, Graham L, Quant J. Pain
management. In: Anesthesia and critical
medicine, St. Paul, MN: 2003
2. Plumb D. Veterinary drug handbook 5th edition.
Ames, IA: Blackwell, 2005.
3. Thurmon J, Tranquilli W, Benson G.
Veterinary Anesthesia 3rd ed. Philadelphia,
PA:1996.
4. Quant J, Lee J, Powell L. Analgesia in
critically ill patients. Compendium of
continuing education for veterinarians, 2005;
June 433-446.