Lecture 9 Anesthesia in Dogs and Cats Part 1

Question 1

What can be done to Prevention of Peri-anesthetic nausea & vomiting

Answer 1

• Give Maropitant (Cerenia) – Neurokinin-1 antagonist 1.0mg/kg subQ at least one hour before opioid premedication
  
  • Prevents vomiting & signs of nausea associated with opioid drugs
  • Faster return to feeding PO

Question 2

What type of drug is Maropitant (Cerenia)

Answer 2

•Neurokinin-1 antagonist

Question 3

Other than preventing vomiting and nausea, what does Maropitant (Cerenia) do?

Answer 3

Adjunct analgesia - ↓MAC sevoflurane in dogs & cats

Question 4

1. What do opoids do to the body
2. MAC?

Answer 4

1. Bradycardia, respiratory depression
   
   • Mild CV effects
2. ↓ MAC of inhalant

Question 5

What are some considerations when choosing an opioid?

Answer 5

1. Pre-emptive pain score – None, mild, moderate, severe pain
2. Duration of action – (Onset of action – buprenorphine)
3. Ceiling effect?
4. Does it cause nausea/vomiting?
   
   • ↑ IOP, ICP, risk for aspiration => brachycephalic, laryngeal hemiplegia, neurologic patients
5. Route of administration – fentanyl requires IV catheter
6. MAC sparing
7. Dog vs cat – mu agonists

Question 6

1. What type of drug is butorphanol
2. Does it cause sedation?
   
   • if so how long does it last?
3. Analgesia?
   
   • if so how long does it last?

Answer 6

1. Kappa agonist-mu antagonist
2. Mild sedation
   
   • 1-2 hours,
3. Mild analgesia
   
   • ~90min.

Question 7

1. Does butorphanol have a ceiling effect?
2. What type of procedures is it used on?

Answer 7

1. ‘Ceiling effect’
2. Non- or mildly painful procedures
   
   • Imaging, minor sx procedure
   • Pre-med to avoid vomiting, full agonist to follow

Question 8

1. What type of drug is buprenorphine
2. Causes sedation?
3. Analgesia?

Answer 8

1. Partial mu agonist
2. Little sedation,
3. mild-moderate analgesia

Question 9

1. Can Buprenorphine be easy to reverse?
2. onset
3. duration
4. Does it have a ceiling effect?

Answer 9

1. Very ‘sticky’ to mu receptor
   
   • difficult to reverse or to follow with mu agonist
2. Slow onset => 30-45min.
3. Duration => Dogs: 4-10 hours, Cats: 6-12 hours
4. ‘Ceiling effect’

Question 10

What are the full mu agonists

Answer 10

1. Hydromorphone,
2. Morphine,
3. Oxymorphone,
4. Methadone

Question 11

1. How much pain do the full mu agonists alieve
2. Duration of actions for each?

Answer 11

1. Moderate – severe pain
2. Duration of action:
   
   • Hydro/oxymorphone: 2-4 hours
   • Morphine, Methadone 4-6 hours

Question 12

Which full mu agonist is also an NMDA antagonist

Answer 12

Methadone

Question 13

What are the side effects of full mu agonists

Answer 13

1. –Nausea, Vomiting, defecation
2. –Dysphoria, Panting
3. –CV effects minimal; bradycardia
4. –Respiratory depression
5. –Hyperthermia in cats
6. –Morphine can cause histamine release if given quickly IV

Question 14

1. What type of drug is fentanyl
2. How much pain does it alleviate?
3. Duration of action?
4. What does it to do MAC of ISO?

Answer 14

1. Full mu agonist
2. Moderate-severe pain
3. Short acting; 20-30 min.,
   
   • requires IV catheter/CRI
4. ↓ MAC of ISO ~65%

Question 15

1. What is a side effect that most full mu agonists that fentanyl doesnt have
2. What are its cardiovascular effects?
3. Respiratory effects?

Answer 15

1. •No vomiting, no histamine release
2. •Mild CV effects -> Bradycardia
3. •Respiratory depression -> Monitor SpO2, IPPV

Question 16

What 2 drugs can be used as an induction agent IV in critical ill patients

Answer 16

1. Fentanyl
2. Midazolam

Question 17

What are the Premedications that are sedatives

Answer 17

1. Acepromazine
2. Dexmedetomidine/Medetomidine
3. Midazolam
4. Diazepam

Question 18

1. What type of drug is Acepromazine
2. Duration of action?
3. Does it have a reversal agent. If so what?

Answer 18

1. Phenothiazine, alpha-1 antagonist
2. Long duration of action 4-6 hours (will last thorough recovery)
3. No reversal agent

Question 19

1. Does acepromazine cause sedation?
2. Analgesia?

Answer 19

1. –Relatively more mild sedation vs dexmedetomidine
2. –No analgesic effects, synergistic effect with opioids

Question 20

1. What are the cardiovascular effects of acepromazine?
2. Which types of animals do you want to give a low dose/ avoid it in?
3. What conditions do you avoid it in?

Answer 20

1. Vasodilation, hypotension,bradycardia
2. Lower dose/ avoid IV,
   
   • geriatric,
   • pediatric,
   • liver dysfunction
3. Avoid in:
   
   • hypovolemia,
   • shock,
   • critically ill,
   • liver failure

Question 21

1. Does Dexmedetomidine cause sedation?
2. Analgesia?
3. Onset of action?
4. Duration of action?

Answer 21

1. Potent sedative
2. analgesia
3. Short onset of action (~5-10 minutes)
4. Short duration of action (may not last throrough recovery)
   
   • May need sedation for recovery to avoid sudden arousal

Question 22

1. What are the cardiovascular effects of Dexmedetomidine
2. What is the reversal agent?
3. What type of patients do you use it in?

Answer 22

1. 40% ↓ CO, reflex bradycardia due to vasoconstriction
2. Atipamazole
3. Reserve for healthy or very painful, fearful, aggressive patient

Question 23

1. Midazolam is good to use in young, healthy dogs?
2. Geriatric, critical patients?
3. What are its cardiovascular effects?

Answer 23

1. Typically NOT good sedative in young, healthy dogs
   
   • Paradoxical excitement
2. effective in geriatric, critical patients
3. Mild cardiovascular effects

Question 24

1. What are midazolams uses?
2. Does it cause amnesia?

Answer 24

1. Uses:
   
   • Induction adjunct => ↓ Propofol induction dose
   • Anti-convulsant => seizure patients
2. Amnesic

Question 25

1. What are the 2 anti-cholinergics? 2. What does it do to vagal effects 3. Salivary secretions?

Answer 25

1. Atropine and Glycopyrrolate 2. ↓ vagal effects 3. ↓ salivary secretions

Question 26

1. Does atropine cross BBB/placenta? 2. Onset of action 3. Duration of action?

Answer 26

1. Crosses BBB/placenta 2. Onset of action (minutes): 5 IM, 1 IV 3. DOA: 60-90 minutes

Question 27

1. Does Glycopyrrolate cross BBB/placenta? 2. Onset of action 3. Duration of action?

Answer 27

1. –Does not cross BBB/placenta 2. –Onset of action: 3 – 5 minutes 3. –DOA: 2-4 hours

Question 28

1. Side effects of Anti-cholinergics 2. What drug and when is it contraindicated?

Answer 28

1. Side effects: sinus tachycardia, 2° A-V block 2. Do NOT use with Dexmedetomidine if high BP

Question 29

•Should you use an anti-cholinergic in premedication?

Answer 29

1. Easier to prevent bradycardia than to treat it * IV anti-cholinergics can cause arrhythmias (see above) 2. Pediatric patients * More dependent on HR for CO 3. Brachycephalic breeds – high vagal tone with upper airway obstruction

Question 30

Which disease process do you avoid anti-cholinergics in?

Answer 30

–Avoid in patients with cardiac disease

Question 31

Give a brief summery of the preanesthetics and what they are based on and indicated/ contraindicated in

Answer 31

1. Opioid Analgesic- Butorphanol, buprenorphine, full mu agonist (or fentanyl IV) * Based on pre-emptive pain score, inhalant sparing needs, cost, availability 2. +/- Sedative – Acepromazine, Dexmedetomidine, Midazolam * Based on signalment, temperment, patient physical status, co-morbidities 3. +/- Anti-cholinergic * Indications: Pediatric, brachycephalic * Contraindications: cardiac disease

Question 32

What are some reasons why cats are NOT small dogs

Answer 32

1. Restraint/Catitude 2. Combination vs single drug sedation 3. Airway issues * Laryngospasm * Tracheal rupture 4. Drug Metabolism 5. Pain Evaluation

Question 33

What are the drug combinations for ‘Kitty Magic’

Answer 33

1. Dexmedetomidine 2. Opoid * Butorphanol * Buprenorphine * Methadone * Hydromorphone 3. Ketamine or tealazol if need more restraint (evil cat) * ↑ restraint (aggressive patients) * analgesia * total injectable anesthesia ​

Question 34

What are the benefits of using dexmedetomidine in "kitty magic"

Answer 34

1. Provides sedation & analgesia 2. Quick onset of action (5-10 minutes) 3. Relatively short duration of action 0.5 – 1.0 hr depending on dose/route 4. Reversible

Question 35

What are the opioids used in "kitty magic"

Answer 35

1. Butorphanol 2. Buprenorphine 3. Methadone 4. Hydromorphone

Question 36

Benefits of using butorphanol in kitty magic

Answer 36

1. short acting ~90 minutes 2. ceiling effect’ =\>↑ dose, no additional analgesia 3. Better sedation than Buprenorphine

Question 37

Benefits of using Buprenorphine in kitty magic

Answer 37

1. Slow onset of action =\> 30-45 minutes\*\* 2. Duration of action =\> 6-12 hours in cats 3. Very ‘sticky’ to mu receptor, difficult to reverse 4. Moderate analgesia, sedation \< butorphanol

Question 38

1. What are side effects of Buprenorphine 2. What is another mode of administration other than IV,SQ,IM 3. Does it cause hyperthermia in cats?

Answer 38

1. Vomiting, dysphoria RARE 2. Good bioavailability with oral transmucosal dosing 3. NOT ASSOCIATED with hyperthermia in cats\*\*

Question 39

1. What are the benefits of using buprenorphine alone with dexmedetomidine 2. Butorphanol pre-med, give Buprenorphine 1 hour later? 3. Give both Butorphanol, Buprenorphine with Dexmedetomidine pre-med?

Answer 39

1. Buprenorphine (alone) with Dexmedetomidine * Less sedation, delayed onset of analgesia * OK if using Ketamine 2. Butorphanol pre-med, give Buprenorphine 1 hour later * Better initial sedation, longer lasting analgesia 3. Give both Butorphanol, Buprenorphine with Dexmedetomidine pre-med * One administration, but larger volume * Opioid interference? * Mu-antagonist + partial mu agonist

Question 40

1. What type of drug is Methadone 2. Mode of administration

Answer 40

1. Mu-agonist, NMDA-receptor antagonist 2. IM, IV, SC

Question 41

1. How much pain does Methadone releave 2. Is there a ceiling effect 3. Duration of action? 4. What effect does it have on cats?

Answer 41

1. Moderate to severe pain 2. No ceiling effect 3. Duration of action ~4 hours 4. Euphoria in cats

Question 42

1. What type of drug is Hydromorphone/Morphine 2. What happens if you give morphine IV rapidly?

Answer 42

1. mu-agonists 2. Morphine- histamine release if given rapidly IV

Question 43

Hydromorphone has been with associated with what side effect in cats?

Answer 43

* hyperthermia * 75% cats had rectal temp \>104, peak temp 108.5 * Related to severity of intra-op hypothermia

Question 44

When and why would you add ketamine or telazol to kitty magic

Answer 44

1. More profound/reliable restraint, add 2-3 mg/kg * if aggressive 2. ‘Excited’ cats may ‘over-ride’ Dexmedetomidine sedation * Additional Dexmeditomidine does NOT ↑ level of sedation * Add 2 - 5mg/kg if cat is ‘resistant’ 3. Less ↓ in HR

Question 45

How long does Ketamine (or Telazol) last in cats?

Answer 45

30 – 40 minutes

Question 46

Give some 'Kitty Magic’ Options

Answer 46

1. Dexmedetomidine + Butorphanol * Short acting sedation, mild analgesia * Give buprenorphine 1 hour after butorphanol for longer, moderate analgesia * Still need induction agent 2. Dexmedetomidine + Ketamine (or Telazol) + Buprenorphine * D & K provide initial analgesia before slow onset of analgesia by buprenorphine (~45 minutes) 3. Dexmedetomidine + Methadone * Moderate-severe pain 4. Add Ketamine or Telazol to any for ↑ restraint or TIA

Question 47

1. Which 'kitty magic' drug causes salivation? 2. Which 'kitty magic' drug decreases salivation?

Answer 47

1. Ketamine based protocols require anti-cholinergic to ↓ salivation 2. Dexmedetomidine is an antisialogue so anti-cholinergic not needed if given with Ketamine