VT 215_Week6_Lecture_Mice+Rats Anesthesia+Analgesia1.pptx

VT 215: Laboratory Animal Science Week 6 Lecture: Mice & Rats: Anesthesia & Analgesia Kati Marshall, CVT, RLATG, CMAR, BS Objectives Know where to find SLA Anesthesia Formularies Understand that (in labs) ALL procedures MUST be approved by IACUC List unique Sx & anesthesia needs as they pertain to...

VT 215: Laboratory Animal Science Week 6 Lecture: Mice & Rats: Anesthesia & Analgesia Kati Marshall, CVT, RLATG, CMAR, BS Objectives Know where to find SLA Anesthesia Formularies Understand that (in labs) ALL procedures MUST be approved by IACUC List unique Sx & anesthesia needs as they pertain to mice & rats Understand that Lab animal medicine has specific requirements Understand that lab animals MUST be treated for pain List pros and cons of both inhalant & injectable anesthesia Understand that No documentation = NEVER HAPPENED Surgery in Laboratory Animals Classification of surgery  Major vs. minor  Major – enters body cavity or impairs movement or physiological function  Minor – does not enter body cavity or cause impairment  Survival vs. non-survival  Survival – animal wakes up  Non-survival – euthanized while anesthetized Would you be able to explain the difference between a major vs minor surgery? Surgery in Laboratory Animals  Implants  Placement of IV access port, indwelling catheter  Telemetry device  Cannulae  Animal  Tumor as surgical model or tissue implants  Study tumor response to treatment  Reproductive studies (Hormone manipulation – ovex, orchiectomy)  Clinical – same as pets Mice & Rats Anesthesia, Sedation, Analgesia U.S. Government Principle V Procedures with animals that may cause more than momentary or slight pain or distress should be performed with appropriate sedation, analgesia, Momentary or slight pain/distress = or anesthesia. blood collection, injection, similar level of invasion and time required to perform procedure When to use anesthesia, sedation or analgesia  Surgery  Certain laboratory procedures  CSF tap  Imaging  When necessary to handle animal safely aka ‘chemical restraint’  To decrease stress during minimally invasive procedure Local anesthetics – aka Locals Nerve blocks: Sx, dental & diagnostic procedures and pain management Infiltration: for minor Sx procedures & dentals Lidocaine Bupivicaine Other -caines Nerve blocks Incision line infiltration Dilution required typically Analgesics – aka pain meds Opioids Buprenorphine Meloxicam BupSR Carprofen Ethique Fentanyl injectable Morphine NSAIDS Analgesics NSAIDS  Meloxicam  Carprofen  Research Considerations:  May interfere with research results  Dilution typically required  Or specialized preparations Analgesics Opioids Buprenorphine BupSR Ethique** Fentanyl injectable Morphine  Dilution typically required  Or specialized preparations Be able to list the PO methods Analgesia administration  IP: Common for initial dose  Sustained release formulations  SQ: Depends on absorption, formulation Would PO be  PO a good  Drinking water  Gel cups  Chews  Gavage option for malocclusio n? Mammals and N0n-Traditional species Finding Formularies Examples from ONPRC Mathing Drug Doses in Small Mammals and N0n-Traditional species Where do you get them?  Textbooks  Journal articles  Formularies  What if there isn’t a dose for the drug/species???  Pilot studies  Direct studies  Extrapolation ▪ May not account for basal metabolic differences  Experience  Advice from colleagues Resources: Formularies, Textbooks, Journals Drug dilution for small rodents  Typically necessary for accurate dosing of mice  Balance:  Ability to accurately measure drugs  Volume for injection site  Ease of administration ▪ Consider needle hub for small volumes ▪ Comfort of animal ▪ Speed of administration ▪ pH & physical parameters of solution  Use sterile saline for injection for dilution  Discard single dose vials after 1 day Med Contains Diluted Oxytocin Common Usage Dosage Notes Dystocia 0.5mls SQ 2nd dose @ 30min Diluted Ketoprofen 1mg/ml (dilute 0.1ml 100mg/ml ketaprofen with 9.9mls sterile saline Analgesia .07mls/30gm NSAID analgesia Tetracycline (liquid) 250mg/ml Diarrhea 18mls/300ml water bottle SIDx7.Replace and repeat for another 7 days Remove 18mls of H20 Add the med Mix well Trimethoprim Sulfa (TMS) Sulfamethoxazol e and Trimethoprim (200mg/40mg per 5mls) General antibiotic .03ml PO Baytril Enrofloxacin 100mg/ml General antibiotic 1.9mls/250mls drinking water Replace weekly Online Calculator for weight dosage: http://reference.medscape.com/calculator/weight-dosing Selecting Anesthetics you list Selection of AnestheticsCan the pros and cons? Injectables  Injectable  Pros: ▪ No need for specialized equipment ▪ May provide analgesia ▪ Easy to administer ▪ IP most common: often longer duration of action compared to IV ▪ No exposure to WAGs ▪ Ideal when unencumbered access to head is needed  Injectables:  Cons: ▪ Titration is challenging ▪ Longer induction and recovery period ▪ Can also be a pro ▪ Increases risk of hypothermia ▪ Risk of peritonitis or bleeding with IP injections ▪ Higher rate of anesthetic complications/death ▪ Controlled substances Injectable Anesthesia/Sedation  Common cocktails:  Ketamine + acepromazine  Ketamine + xylazine  Ketamine + xylazine + acepromazine  +/- Benzodiazepines as adjunctive agent  Pentobarbital for specific projects  Type of research and effects of anesthetic agents are key considerations Mouse Injectable Anesthesia https://animal.research.uiowa.edu/iacuc-guidelines- Selection of Anesthetics Inhalants Can you list the pros and cons?  Pros:  Rapid induction and recovery ▪ Can also be a con  Rapid titration to effect  Lower rate of anesthetic complications/de ath  Cons: ▪ Specialized equipment required ▪ Potential exposure to WAGs ▪ Face mask may obstruct procedures around the head ▪ Some species (hedgehogs) hold their breath ▪ Some species have a lag in response & then are overly anesthetized (ferrets) Inhalant anesthesia  Isoflurane most common  Induction = Chamber  Maintenance = Typically via mask/nosecone  Rodents are obligate nose breathers  Non-rebreather set-up  Indications for intubation ▪ Surgery involving head ▪ Thoracotomy Inhalant anesthesia: Ind uction Inhalant anesthesia: Maintenance Inhalant anesthesia: Low flow Intubation of Small Rodents NOT ROUTINELY DONE DUE Poisseuille’s Law TO Intubation of small rodents  Not routinely done  Why? Can you describe what Poisseuiile’s Law is, and how it relates to mouse anesthesia?  Poisseuille’s Law ▪ Fluid dynamics of laminar flow ▪ Small change in airway diameter leads to big changes in airway resistance ▪ 50% decrease in airway diameter = 16X increase in resistance Intubation of small rodents Rivard, et al, Journal of Investigative Surgery, 19:2676274, 2006 Intubated small rodents must be ventilated Ventilators for small mammals Necessary for intubated rodents These machines are Automatic Ventilators for rodents - you’ll want to remember that term Surgical Standards for Small Laboratory Rodents Brought to us by the letter “G”, for The Guide for the Care and Use of Laboratory Animals Pre-Operative Prep Anesthetic Depth Peri-Operative Monitoring & Support Post-Procedural Monitoring Surgical Standards  The Guide for the Care & Use of Laboratory Animals  Successful surgical outcomes require appropriate attention to: presurgical planning  personnel training  anesthesia  aseptic and surgical technique  assessment of animal well-being  appropriate use of analgesics  animal physiologic status during all phases of a protocol involving surgery and postoperative care Pre-operative Preparation Patient Preparation  Remove hair  Clippers  Nair  Sterile prep  Povidone iodine  Chlorhexidine  Drapes  Clear drapes are best for monitoring Pre-operative Preparation Equipment sterilization  Autoclave  Ethylene oxide  Bead sterilizer  Chemicals  Povidone iodine  Chlorhexidine  Glutaraldehyde Anesthetic depth Which reflex is best for assessing mice? 1. Pedal reflex  Most accurate reflex in rodents 2. 3. 4. 5. 6. Lack of purposeful movement Loss of righting reflex Respiratory rate and character Lack of response to external stimuli Pinnal response  Most useful in rabbits 7. Ocular position  Not useful in rodents 8. Palpebral reflex  Not useful in rodents 9. Tail pinch – more useful with rats ASSESS MORE THAN ONE REFLEX! Stages of Anesthesia  Stage 1  Excitatory  Disorientation, vocalization, urination, defecation  Stage 2  Loss of consciousness, +/- paddling/movement  Loss of righting reflex (many other reflexes still intact)  Rigidity, rapid irregular breathing  Stage 3  Surgical stage of anesthesia  Loss of reflexes  Muscle relaxation, deep and rhythmic breathing  Planes 1-4 (light to deep)  Stage 4 : Not Desirable!  Medullary paralysis with respiratory arrest  Hypotension and imminent death  CPR and reversal agents required or animal will die. Small mammal https://lafeber.com/vet/anesthetic-depth-in-exotic-animals-monitoring-the-degree-of-central-nervous-system-depre ssion/ Pollock CG, Nugent-Deal J. Anesthetic depth in exotic animals: monitoring the degree of central nervous system Large mammal Peri-operative Monitoring Specialized monitors required Temperature Respiratory rate Heart rate Pulse oximetry Capnography Blood pressure Can you list the #1 cause of perioperativ e death? Peri-operative Support  Heat  Warm water pad  Right Temp pads  Snuggle safe disc  Hot Hands  Baer hugger  Must prevent hypothermia! ▪ #1 cause of perioperative death  Fluids  Subcutaneous  Intraperitoneal  Eye lubrication (why is this important?) Post-procedural monitoring REQUIRED by IACUC Pain Rx must be administered according to protocol Rx must be documented Distress Adverse reactions RECORD KEEPING!!! Monitoring Pain  U.S. Government Principle IV Would you assume something that hurts you, would also hurt an animal?  “Unless the contrary is established, investigators should consider that procedures that cause pain or distress in human beings may also cause pain or distress in other animals.”  AALAS Position Paper: Alleviating Pain & Distress in Laboratory Animals  https:// www.aalas.org/about-aalas/position-paper s/alleviating-pain-and-distress  Read on your own; focus on: ▪ Humane Endpoints ▪ If signs of pain are the same across species Monitoring Pain  Difficult in rodents  Animals are often stoic ▪ Prey species  Signs of pain are subtle  Signs of pain are not apparent Pain Scoring Systems  Objective criteria  Weight, food intake, types of activities  Behavior/absence of behavior ▪ Nest building ▪ Burrowing  Consistent across multiple observers  Specific to a particular species  Rats different from mice  Specific to the kind of pain  Acute different from chronic  Requires extensive training of observers  Videotaping Pain in Rodents  Hunched posture  Lethargic  Flinching  Abdominal press  Writhing  Abdominal stretch  Chewing at incision Grimace Scale Grimace Scale Data Collection  Accurate pain scoring requires extensive, remote observation  Assessment during active phase is most accurate  Need baseline scoring for comparison ▪ Habituate to chamber first  Videotaping ▪ Software frames and captures images of face ~ q 2-3 minutes ▪ Video for 30-45 minutes  Still photographs ▪ Multiple images over defined time periods  “Live” assessments are challenging. Why? Rat Grimace Scale 4 Criteria Assessed: 1. Orbital Tightening 2. Nose/Cheek Flattening 3. Ear Changes 4. Whisker Change Rats: Orbital Tightening 0 1 2 e: Closed eyes without orbital tightening is evidence of relaxation (not p Higher numbers = painful animal Rats: Nose/Cheek Flattening 0 1 2 Higher numbers = painful animal Rats: Ear Changes 0 1 2 Higher numbers = painful animal Rats: Whisker Change 0 1 2 Higher numbers = painful animal Mouse Grimace Scale 5 Criteria Assessed:​ 1.Orbital Tightening​ 2.Nose Bulge 3.Cheek Bulge 4.Ear Position 5.Whisker Changes Mouse: Orbital Tightening 0 1 2 Higher numbers = painful animal Mouse: Nose Bulge 0 1 2 Higher numbers = painful animal Mouse: Cheek Bulge 0 1 2 Higher numbers = painful animal Mouse: Ear Position 0 1 2 Higher numbers = painful animal Mouse: Whisker Changes 0 1 2 Higher numbers = painful animal Grimace Scale Scoring  Per photo:  Grimace scale score= Sum of each “action unit” ▪ Some scales use the average of the action unit sums ▪ Must also score baseline photos ▪ Baseline may not be zero ▪ Scorer must be blinded to condition (baseline v postprocedure)  Pain score = (Post-procedure GS score) – (Baseline GC score)  Establish a pain scoring chart ▪ Cut-offs for pain/possible pain/no pain ▪ When is treatment (or additional treatment) needed? ▪ In humans: Higher numbers = painful animal ▪ Change of 2 points from baseline is considered clinically important Wrap-Up  All procedures MUST be approved by IACUC  Mice & rats have unique Sx needs  Lab animal medicine has specific requirements  Animals MUST be treated for pain  No documentation = NEVER HAPPENED Did we meet these objectives? Know where to find SLA Anesthesia Formularies Understand that (in labs) ALL procedures MUST be approved by IACUC List unique Sx & anesthesia needs as they pertain to mice & rats Understand that Lab animal medicine has specific requirements Understand that lab animals MUST be treated for pain List pros and cons of both inhalant & injectable anesthesia Understand that No documentation = NEVER HAPPENED Questions?