Cox1&2
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This document discusses pain management in veterinary medicine. It begins by explaining why treating pain in animals is important. It then discusses common myths about pain and outlines the physiological effects of pain. The document details different types, classifications, and assessments of pain. It provides an overview of various analgesic options including opioids, alpha-2 agonists, steroids, NSAIDs, local anesthetics, and complementary methods. It discusses considerations for analgesic administration and monitoring pain in animals.
Cox1&2
- 2. Why Treat Pain? Animals feel pain just like us Unethical not to address pain Animal owner and public concerns Many anesthetics have no analgesic effect Which do? Pain results in poor anesthetic recovery
- 3. MYTHS “ Anesthetics mask symptoms” “ Patient will harm itself if there’s no pain” “ Pain is difficult to assess”
- 4. The Truth! Pain is BAD: Decreased cardiovascular function Decresed appetite Slows wound healing Decreased immune function Greater chance of infection Increased fear and anxiety
- 5. Use of Analgesics in Practice Overall = poor 13-26% dog and cat spay/neuters receive analgesics 50-70% of non-neutering soft tissue surgery >80% orthopedic surgery and severe trauma Why not better? DEA / theft concerns Older vets not trained that way Older drugs dangerous Animals are stoic
- 6. Pain Perception Pain sensor nerve fiber spinal cord brain Neurotransmitters>> Somatic ( superficial ) pain Visceral ( internal organ ) pain Bone pain
- 7. Classification of Pain Intensity (scale of 1-10) Acute, sharp, sudden, short Surgical pain Responds well to drug tx Chronic, dull, prolonged Cancer or arthritis Doesn’t always respond well to tx Referred (from somewhere else) Hyperesthesia (increased sensitivity) Neuropathic (Nerve damage) Poorly responsive
- 8. Degree and Type of Pain Depend On The procedure The animal Pain is an individual experience Tailor analgesic protocol to the patient Analgesic administration Timing Dosage
- 9. Preemptive Analgesia If the body doesn’t sense the pain during the procedure, the pain will be easier to deal with post-operatively A patient in surgical anesthesia is not aware of pain, but the body is still responding sensitizes the nervous system
- 10. Preemptive Analgesia Results In Marked decrease in amount of analgesic medication needed post-operatively Increased patient comfort
- 11. Balanced Anesthesia Several anesthetic drugs are combined into anesthetic protocol Include analgesic Synergism Smaller dosages needed Decreased potential for side effects
- 12. Monitoring Signs of Pain Facial Expression Vocalization Body Posture Abnormal Gait Decreased Activity Level Attitude Appetite Grooming Urination/Defecation Habits
- 13. Methods of Pain Control Non-pharmacological methods: Endorphins = The body’s natural painkillers Good nursing care Comfortable bedding Clean and dry Easy access to bathroom, food, water TLC Rotate recumbency Allow time to sleep
- 14. Non-pharmacological Methods Apply cold to site (acute- 1 st 24 hours) Decreases inflammation Numbs Apply heat to site (chronic) Massage Acupuncture/acupressure Complementary methods Herbs, laser, magnetic, chiropractic
- 15. Pharmacologic Methods Opioids 2 agonists Steroids NSAIDS Local anesthetics Chondroprotective drugs
- 16. Opioids
- 17. Opiate Receptors MOA? 4 types of receptors: mu kappa sigma delta Should we be wondering why fraternities/sororities name themselves after receptors of pain??
- 18. Opioids: Backbone of Analgesia Pure Agonists Morphine, oxymorphone, meperidine, hydromorphone, fentanyl Partial agonists, mixed agonist-antagonists Buprenorphine Butorphanol Pure Antagonists (reversal of agonists) Naloxone ABUSE POTENTIAL
- 19. Opioid Administration Systemic: IV, SQ, IM, CRI Intra-articular injection Local injection Epidural injection Transdermal fentanyl patch
- 20. Opioid Effects GOOD: Great analgesia Variable muscle relaxation Sedation BAD: Respiratory depression GI effects Vomiting Defecation followed by constipation
- 21. Opioids (other effects) Excitement Panting Vocalization Noise sensitivity Depression of the cough center Advantage for?
- 22. Fentanyl Patch Lag time: apply 6-12 hours prior to surgery in cats, 12-24 hours in dogs Lasts about 3 days (up to 6 in cats) Variation in absorption rate Dose of patch (in micrograms/hr) Avoid heat sources Excessive amounts can cause ataxia, sedation in dogs, excitement, disorientation, wide-eyed stare in cats Remove patch, can reverse
- 23. Fentanyl Patch Applied to dorsal neck or shoulders, lateral thorax Clip hair, clean skin with water only Do not cut patch Can remove just part of backing if small animal Apply patch, hold firmly 2 minutes Bandage
- 24. Opioid Partial Agonists Buprenorphine Buprenex® 4-8 hour duration
- 25. Opioid Mixed Agonist-Antagonist Butorphanol (Torbutrol®, Torbugesic®) For mild to moderate pain Duration 1 to 4 hours IM, SQ Less abuse potential than agonists
- 26. Opioid Antagonists Naloxone Used to reverse opiates/opioids Remember: Reverses analgesia too! May not last as long as the agonist Relapse =“renarcotization” Partial reversal with butorphanol possible
- 28. Alpha-2 Agonists MOA? Examples: Xylazine (Rompun ® ) Medetomidine (Domitor ® ) Engages receptors in CNS >> decrease norepinephrine
- 29. Xylazine: Good Things Moderate analgesia Potent sedative effect Good muscle relaxation
- 30. Xylazine: Bad Things Bradycardia due to stimulation of the vagus nerve heart block Profound cardiac disturbances! Sensitizes the heart to catecholamines Arrhythmias Decreased cardiac output Hypotension (BP decreases by 1/4-1/3) #1 ?
- 31. Xylazine: More Bad Things Vomiting (sometimes used as emetic)
- 32. Xylazine: Reversal? Yohimbine is reversal agent Mixed Alpha- antagonist (blocker) Trade name “Yobine”
- 33. Medetomidine =DOMITOR® More specific to CNS alpha-2 receptors Alpha-2 so has reversal agent (Antisedan®) Common name? Name?
- 34. Steroids = corticosteroids,glucocoticoids Examples: Prednisone = Prednisolone Dexamethasone Betamethasone Solu-Delta-Cortef Solu-Medrol Decrease pain by decreasing inflammation
- 35. Steroids: MOA inhibit phospholipase A2>>> inhibits prostoglandin/leukotrienes COX-2 COX-1 Phospholipase A2 Steroids inhibit here NSAIDS inhibit here Membrane Phospholipid Arachidonic Acid “ Bad” Prostaglandins Pain/Inflammation “ Good” Prostaglandins GI Protection Renal Blood Flow Thromboxane “ Platelets”
- 36. Side Effects and Toxicity Iatrogenic hyperadrenocorticism “ Cushings Dz” Polyphagia PU/PD Glaucoma and cataracts Gastric ulceration Delayed wound healing Immunosuppression
- 37. More ! Insulin resistance Hepatopathy CNS: restlessness, seizure activity Infection
- 38. Non-Steroidal Anti-inflammatory Drugs ( NSAIDS ) Aspirin Carprofen - Rimadyl ® Etodolac - Etogesic® Ketoprofen - Ketofen ® Phenylbutazone – “Bute” Flunixin - Banamine ® (Acetaminophen - Tylenol ®)
- 39. NSAIDS Most have effective somatic (superficial) analgesic effect Some have good visceral analgesic effect also All take 30-60 minutes to take effect, even if injected All have antiinflammatory properties Reduce fevers
- 40. NSAIDS MOA: cyclooxygenase inhibitors >> prostaglandin inhibitors Many side effects are due to “good” prostaglandin inhibition (COX 1): GI upset/ ulceration Renal toxicity Impaired platelet function
- 41. NSAIDS: MOA inhibit cyclooxygenase>>> inhibits prostoglandin/thromboxane COX-2 COX-1 Phospholipase A2 Steroids inhibit here NSAIDS inhibit here Membrane Phospholipid Arachidonic Acid “ Bad” Prostaglandins Pain/Inflammation “ Good” Prostaglandins GI Protection Renal Blood Flow Thromboxane “ Platelets” Fever
- 42. NSAIDS - Metabolism Metabolized by the liver Variation in metabolism between species Aspirin half-life 12 hours in dogs, 1 hour in horses, 38 hours in cats Many NSAIDS toxic to cats due to inability to metabolize them Acetaminophen is toxic in dogs AND cats!
- 43. NSAIDS Inhibit Production of Protective GI Prostaglandins Erosion/ulceration of GI tract Stomach upset Inappetance Vomiting Diarrhea Melena ?
- 44. Prostaglandins in the Kidneys Cause dilation of renal vasculature, allowing perfusion despite decreased blood pressure due to Shock Dehydration Blood loss Anesthesia Inhibition of prostaglandin production can cause kidney cell death due to lack of perfusion Only an issue if decreased BP
- 45. NSAIDS Cyclooxygenase inhibition decreased thromboxane decreases platelet adhesion/clumping decreases clot formation and thromboemboli
- 46. TYPES of NSAIDs
- 47. Phenylbutazone COX1 and 2 Inhibitor Very Potent Commonly used in horses Not recommended in dogs GI side effects common NEVER IN CATS!
- 48. Aspirin COX1 and 2 Inhibitor Very short half-life in horses Commonly used in dogs Buffered only With food Use with caution in cats Can’t metabolize well Half-life 38 hours Dosed every 48-72 hours
- 49. Neither Ibuprofen Nor Naproxen Is Recommended for Use in Cats Ibuprofen = “Advil” COX1 + COX2 Inhibitors Officially not recommended in dogs. most do OK if used like aspirin
- 50. Ketoprofen Ketofen ® (COX1 and COX2) Licensed in horses Approved for use in dogs and cats in Canada, Europe Good analgesia, potent antipyretic Injectable Limit use Blood clotting
- 51. Flunixin meglumine Banamine ® (COX1 and COX2) Injectable Horses Colic Good analgesia Dogs GI side effects common, severe
- 52. Carprofen Rimadyl ® COX-2 inhibitor: “spares” “good” prostaglandins Fewer side effects DOGS ONLY Black labs… 0.06% of all dogs develop hepatic problems (rare) BID Dosing
- 53. Etodolac Etogesic ® COX 1 and 2 Inhibition Once daily administration DOGS ONLY
- 54. Derramax Use in dogs COX 2 Specific SID dosing $$
- 55. “ Metacam” =Meloxicam COX-2 Specific Use in dogs and cats Liquid Well tolerated $$
- 56. NSAID Precautions Use only 1 NSAID at a time Never combine NSAIDS with glucocorticoids Gastric Ulceration Taper to lowest effective dose Change to alternative NSAID if poor response
- 57. NSAID Contraindications Renal of hepatic dysfunction Decreased circulating blood volume Coagulopathies GI disease Pregnancy
- 59. Local Anesthetics The “-caine” family: Lidocaine, bupivicaine, mepivicaine, proparicaine, tetracaine, etc. MOA= Block nerve impulses by blocking Na+ channels in nerve membranes
- 60. Local Anesthetics Local infiltration of surgical site Intravenous regional anesthesia Intra-articular injection Nerve blocks Epidural Topical on skin/ eye/ larynx http://www.cvm.okstate.edu/courses/vmed5412/Lect23.asp
- 61. Commonly Used With Neuroleptanalgesic
- 62. Capsaicin Hot peppers Excites then fatigues nerve transmission local analgesia Also get endorphin release
- 63. St. Johnswort Arthritic pain Hypericin Stimulates neural inhibitory pathways analgesia
- 64. Chondroprotective Agents Nutraceuticals Chondroitin sulfate Glucosamine Hyaluronic acid Building blocks for cartilage and synovial fluid Examples: (oral) Synovi, Glycoflex (injectable) Adequan Can be mixed with many other ingredients (MSM, Creatine) to enhance effects.
- 65. Antibiotic Analogy to understand pain control Antibiotics prescribed based on clinical signs, not always based on culture and sensitivity Rely on return to normal function to confirm diagnosis If doesn’t help, add to or change drug protocol May need a loading dose May need a combination of drugs
- 66. Questions ??