The Pathophysiology of Pain, Our Veterinary Patients, And you… What Can or Should Be Done? Andrew Claude DVM, Dipl ACVAA Michigan State University College of Veterinary Medicine [email protected] Objectives • Definitions. • Process of Nociception. • What is pain? • AVMA/ACVAA regarding pain. • Patient – client considerations • Pain management in medicine • Clinical signs of pain in dogs/cats • Preemptive analgesia options • Pain scores in dogs and cats (if time) Definitions • Anesthesia = analgesia = analgesic? Clinician's Brief • General anesthesia: General vs. local and regional anesthesia • Analgesia: the inability to feel pain • Analgesic: any member or group of drugs used to achieve analgesia or relief from pain. • Analgesia →Nociception • Acute vs. Chronic pain, neuropathic pain Process of nociception • Transduction • Aβ, Aδ, c-Fibers, silent • Transmission • Dorsal horn, CNS • Primary Modulation • Segmental reflexes • Projection • Perception • Conscious Pain • Autonomic (SNS) • Memory • Emotions • Central/peripheral • Humans/animals What is pain? • Definition: “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.” • Sensory component (nociception) • Affective component (experience) • Considered the 5th clinical sign • HR • RR • Temp • BP • Pain assessment What is pain? • Requires conscious perception of a noxious event • Do unconscious patients perceive pain? • Nociception: “the neurophysiological process whereby noxious mechanical, chemical, or thermal stimuli are transduced into electrical signals (action potentials) by high-threshold nociceptors.” These action potentials follow a series of pathways that ultimately end in the brain • The conscious result is “pain” AVMA • Pain in Animals • Animal pain is a clinically important condition that adversely affects an animal's quality of life. Drugs, techniques, or husbandry methods should be used to prevent, minimize, and relieve pain in animals experiencing or expected to experience pain. Protocols must be tailored to individual animals and should be based, in part, on the species, sex, breed, age, procedure performed, degree of tissue trauma, individual behavioral characteristics, assessment of the degree of pain, and health status of the animal. https://www.avma.org/KB/Policies/Pages/Pain-in-Animals.aspx ACVAA • Position on treatment of pain in animals • Animal pain and suffering are clinically important conditions that adversely affect quality of life, short or long term. • Endorses a philosophy that promotes prevention and alleviation of animal pain and suffering as an important and tenable therapeutic goal. • Clinically, unrelieved pain does not provide any benefit in animals; therefore, veterinarians should strive to manage pain in animals under their care. • Treatment of pain can be considered successful if the degree of pain does not prevent an animal from engaging in relatively normal activities, such as eating, sleeping, ambulating, grooming, and interacting with other members of its species or its care givers. • Nevertheless, every attempt should be made to prevent or alleviate pain in animals unless there are compelling reasons to withhold treatment. • The ACVAA's position is in accordance with the Veterinarians' Oath, in which each member admitted to our profession pledges to "... use my scientific knowledge and skills for the benefit of society through ...the relief of animal suffering...." The ACVAA's position is also in accordance with recommendations of the National Research Council published in the "Guide for the Care and Use of Laboratory Animals". http://www.acvaa.org/docs/Pain_Treatment Questions… • How is vet med doing regarding acute pain management for our patients? • Better.. • How is vet med doing regarding chronic pain management for our patients? • Not so good.. • Antiquated information? • Do our animal patients experience chronic pain? • If not, why not? • Process of nociception is almost identical to humans. • If so, how do we identify chronic pain • Historical information • Visible signs (coat) • Physical exam (TMJ) including gait analysis • Myofascial palpation (myofascial changes, TPs, taught bands) • If so, how do we manage chronic pain in our animal patients? • Ignorance = chronic ignoring? Client Communication • Because our patients cannot directly communicate to us, client communication is our BEST tool for patient welfare needs. • Overall, how well do we communicate with our clients? • Depends.. • Contrast a canine surgery with a similar surgery in humans, regarding communication how do we compare? (ACL injury and Sx. Repair) • What muddies the water? • Client expectations/misunderstandings • Practitioner knowledge/experience/expectations • Under the bestest circumstances what would you do? Patient-client considerations Dogtime • Owners should receive pain management (pre, intra, post-op) information and have questions answered before procedures. • Clear, concise plan with logical, sequential goals, including alternate options • Caregivers should be educated on the source and potential effects of their pet’s pain (surgical, degenerative, cancer, etc.) • Options for treatment of pain should include collaborative, science-based integrative medicine. • Myofascial palpation • Patients should routinely be reassessed for pain. • How often? • Caregivers and veterinarians need to communicate openly about pain. • Nociception similar btw humans and animals; why are we still struggling with this concept? Narda G. Robinson DO, DVM, MS, FAAMA, Curacore Integrative Medicine and Education Center Pain management in medicine • Human Medicine • Veterinary Medicine… • NPF = Five Pillars Pain Mgmt. • Emotional and cognitive comfort • Physical restoration • Physical restoration via therapy and • Depends… rehabilitation • Pain medication • Interventional pain procedures • Pain medication • Integrative pain management • Kinda-sorta • Acupuncture • Butorphanol • Phototherapy (LLL) • NSAIDs • Massage • Animal (patient) has to hurt.. • Won’t move, eat, be comfortable.. nationalpainreport.com/national-pain-foundation • Owner options…analgesics Do your clients understand? A reality.. Projection Primary Modulation Perception Multimodal Analgesia!! Transmission Transmission What happens if…? • Peripheral Wind-up • Injury • Inflammatory soup • Hyperalgesia • Silent nociceptors • Conversion Aβ fibers • AMPA • Glutamate • Centralized Pain • Glutamate-NMDA • Subst-P – NK1 • Loss of inhibition • Glial-neuronal interactions • Central wind-up • Neuropathic nociception Clinical signs of pain • Dogs and Cats • Continued • Reluctance to move • Facial expressions • Reluctance to lie down • Trembling or shaking • Constantly shifting positions • Tachypnea or panting • Licking lips • Depression • Submissive/guarding position • Myofascial changes • Aggression • Bottom line… • Vocalization • Hair coat changes/grooming • Changes vital signs Preventive analgesia • Preemptive zoetisUS.com McKesson Medical-Surgical • Intra-operative zoetisUS.com • Post operative • Immediate Medplus Physician Supplies • Pain management no longer needed Henry Schein • Alpha 2 agonists • Dexmedetomidine (careful w/ heart Preemptive analgesia murmurs) • What dose do you use as a premed? • Administering analgesia before • Local and regional nociceptive event significantly • Lidocaine decreases the likelihood of • Bupivacaine (availability) centralized, wind-up pain • Ropivacaine (hypersensitivity). • Nocita (bupivacaine liposome) • Opioids • What about these?? • Butorphanol • Midazolam • Hydromorphone • Acepromazine • Morphine • NSAIDs…. Uh oh, preemptive?! • Buprenorphine • Methadone • Misc. • Gabapentin • Maropitant Pinterest • JVIM, 2013: Systematic Review of Nonsteroidal Anti-Inflammatory Drug-Induced Adverse Effects in Pre-operative NSAIDs.. Dogs, Monteiro et.al • ID and critically evaluated the quantity and quality of evidence • Is SAFE!! • NSAIDs - incidence of adverse effects • Common sense.. vs. placebo • • Concern: CV, Renal, Hypotension Extremely low strength of evidence • Flunixin meglumine, ketorolac, • SNS—> Angiotensine II—> Renal licofelone, rofecoxib, tepoxalin, vessels —> vasoconstriction tolfenamic acid, and vedaprofen • Afferent arterioles are protected due • Methoxyflurane to release of vasodilators • Prostaglandins (PGE2 and PGI2), • High strength of evidence bradykinin, and nitric oxide • carprofen, firocoxib, and meloxicam, • Inference: Inhibition of prostaglandins during surgery may lead to decreased • Renal function tests failed to detect GFR and renal blood flow. renal adverse effects after NSAIDs administration in dogs undergoing general anesthesia and submitted to hypovolemic, hypotensive stress, or both. Intra-operative • Inhalant anesthetics • Intermittent Injections • Analgesia ? • Opioids • IV Constant rate infusions • Lidocaine • Opioids • Ketamine • Fentanyl/Sufentanil • Dexmedetomidine • Hydromorphone • Local and Regionals • Morphine • Nerve blocks • Lidocaine (not cats) • Soaker catheters • Ketamine • Nocita • Dexmedetomidine MAC…..the reality!!! • MAC levels vary • Degree of stimulus • MAC awake • MAC for intubation • MAC no movement • MAC-BAR • MAC-BAR = MAC-NM? • Individual responses • Non-pharmaceutical Post operative • Immediate post-op • Patient comfort • Pharmaceuticals • Ice • • Body temp NSAIDs • Human presence • Galliprant (grapiprant) • Long-term • Opioids • Rehabilitation • BIG concerns…! • Integrative therapy • Buprenorphine • Acupuncture • Photomedicine • Butorphanol