Anesthesia and Analgesia

Question 1

In Henry’s 2014 study “Evaluation and clinical use of an intraoral inferior alveolar nerve block in the horse,” what was the only complication noted and how often were recheck examinations performed?

Pusterla, Verstraete. EVJ 2014

Answer 1

Abscessation of pterygoid fossa 1 horse
24h, 2 weeks, 4 weeks post op

Question 2

In Henry’s 2014 study “Evaluation and clinical use of an intraoral inferior alveolar nerve block in the horse,” what percent of blocks were clinically successful?

Pusterla, Verstraete. EVJ 2014

Answer 2

100%

Question 3

In Henry’s 2014 study “Evaluation and clinical use of an intraoral inferior alveolar nerve block in the horse,” the black arrow highligths what structure and an intraoral IANB should be performed what direction in relation to that structure?

Pusterla, Verstraete. EVJ 2014

Answer 3

Black arrow: palatoglossal arch
Injection should be lateral to the palatoglossal arch

Question 4

In the image below what do the black arrow heads, black arrow, green arrow and white arrow represent?

Henry. “Evaluation and clinical use of an intraoral inferior alveolar nerve block in the horse,” EVJ 2014

Answer 4

Black arrowheads: Facial nerve branches
Black arrow: inferior alveolar artery
Green arrow: Mylohyoid nerve
White arrow: Lingual branch of trigeminal nerve

The white arrowheads are the cut edge of the mandible

Question 5

What nerve is depicted by the white arrow?

Rice, JVD 2017, issue 2, Step by Step Regional Nerve Blocks for Equine Dentistry

Answer 5

Maxillary nerve

Rice recommended 10-20ml here

Question 6

What are the landmarks to palpate for the infraorbital nerve block?

Rice, JVD 2017, issue 2, Step by Step Regional Nerve Blocks for Equine Dentistry

Answer 6

Palpation landmarks for the infraorbital nerve block include the nasoincisive notch (white-dashed arrow) and the rostral border of the facial crest (black-dashed arrow).1

Rice recommends 3 ml here

Question 7

Manual elevation of what muscle facilitates placing the needle within the mental foramen to block the nerve?

Rice, JVD 2017, issue 2, Step by Step Regional Nerve Blocks for Equine Dentistry

Answer 7

depressor labii inferioris muscle

Rice recommends 3 ml here

Question 8

What volume of anesthetic agent is recommended for the mandibular nerve block in this step by step?

Rice, JVD 2017, issue 2, Step by Step Regional Nerve Blocks for Equine Dentistry

Answer 8

Intraoral approach: 10ml
Extraoral approach: 10-12ml

Question 9

In Muller’s 2017 study “Effect of butorphanol, midazolam or ketamine on romifidine based sedation in horses during standing cheek tooth removal”, which sedation group was best at reducing chewing behavior?
A. Romifidine
B. Romifidine with butorphanol
C. Romifidine with midazolam
D. Romidifidine with ketamine

BMC Vet Res 2017

Answer 9

C. Romifidine with midazolam

probably related to the relaxation of the masticatory muscles caused by midazolam

Question 10

In Muller’s 2017 study “Effect of butorphanol, midazolam or ketamine on romifidine based sedation in horses during standing cheek tooth removal”, which sedation group needed the most additional boli of romifidine?
A. Romifidine
B. Romifidine with butorphanol
C. Romifidine with midazolam
D. Romidifidine with ketamine

BMC Vet Res 2017

Answer 10

A. Romifidine

Question 11

In Johnson’s 2019 JVD study on an US guided inferior alveolar nerve block, what is depicted by the red and blue arrows (this is the right side of the horse)

JVD 2019 issue 1

Answer 11

Blue: mandibular nerve
Red: lingual nerve

Question 12

In Tanner’s 2019 study “A Retrospective Study of the Incidence and Management of Complications Associated with Regional Nerve Blocks in Equine Dental Patients” what was the incidence of complications with nerve blocks, and what was the most common complication?

JVD 2019 issue 1

Answer 12

2.96%
Hematoma

Question 13

In Johnson’s 2019 study “Ultrasound-Guided Inferior Alveolar Nerve Block in the Horse: Assessment of the Extraoral Approach in Cadavers”, what % of lingual nerve staining was noted when 2.5ml volume was used? what % when 5 ml used?

JVD 2019 issue 1

Answer 13

2.5ml: Lingual nerve stained in 5/8 (62.5%) of the injections
5ml: Lingual nerve stained in 4/8 (50%) injections

Overall success of staining the inferior alveolar nerve was 75% and 65% respectively for the volumes

Question 14

In Johnson’s 2019 study “Ultrasound-Guided Inferior Alveolar Nerve Block in the Horse: Assessment of the Extraoral Approach in Cadavers”, what % success was noted on CT for 2.5ml volume and 5 ml volume respectively?

JVD 2019 issue 1

Answer 14

Smaller injection volume (2.5ml) successful in 75% injection compared to larger injection volume (5ml) 87.5% cases

Overall success 81% on CT – differed from overall success 68.8% for dissection of methylene blue staining

Question 15

In Gozalo-Marcilla’s 2019 paper “Sedative and antinociceptive effects of different detomidine constant rate infusions, with or without methadone in standing horses,” which protocol produced the most intense and persistent antinociceptive effects?

EVJ 2019

Answer 15

Higher detomidine dose combined with methadone (DHM)

Question 16

In Gozalo-Marcilla’s 2019 paper “Sedative and antinociceptive effects of different detomidine constant rate infusions, with or without methadone in standing horses,” what protocols lead to reduced gastrointestinal motility and for what duration?

EVJ 2019

Answer 16

All treatments reduced gastrointestinal motility
scores returned to baseline sooner for the low dose detomidine and low dose detomidine plus methadone groups

Question 17

In Weber’s 2019 study “Ex vivo evaluation of the distribution of a mixture of mepivacaine 2% and iopromide following local infiltration of the infraorbital nerve via the infraorbital foramen,” what variable was associated with higher canal filling %?
A. volume 10 ml
B. volume 15 ml
C. age
D. legnth of needle

EVE 2019

Answer 17

C. age

Question 18

In Weber’s 2019 study “Ex vivo evaluation of the distribution of a mixture of mepivacaine 2% and iopromide following local infiltration of the infraorbital nerve via the infraorbital foramen,” what % of canals had complete legnth filling associated with the 10 ml volume and 15 ml volume respectively? Was this stat significant?

EVE 2019

Answer 18

10 ml volume: 90%
15 ml volume: 70%
Not statistically signficant

Question 19

In Weber’s 2019 study “Ex vivo evaluation of the distribution of a mixture of mepivacaine 2% and iopromide following local infiltration of the infraorbital nerve via the infraorbital foramen,” what % of the canal was filled by the 10ml volume?

EVE 2019

Answer 19

86.9%

So 90% of the blocks were filled 86.9% in volume

Question 20

In Weber’s 2019 study “Ex vivo evaluation of the distribution of a mixture of mepivacaine 2% and iopromide following local infiltration of the infraorbital nerve via the infraorbital foramen,” what % of the canal was filled by the 15ml volume?

EVE 2019

Answer 20

74%

So 70% of the blocks were filled 74% in volume

Question 21

In Rawlinson’s 2018 study “Evaluation of the equine mental foramen block: cadaveric and in vivo injectate diffusion,” what technique was determined to be most efficacious?

Vet Anes 2018

Answer 21

T2 → needle inserted in a dorsolateral to ventromedial direction with shaft of needle 40 degrees lateral to the parasagittal plane of the lateral mandible and 25 degrees dorsal to the dorsal plane of incisive-premolar interproximal space to depth of 1cm into canal

Question 22

In Rawlinson’s 2018 study “Evaluation of the equine mental foramen block: cadaveric and in vivo injectate diffusion,” what pattern of injectate distribution and needle placement was seen for T1 vs T2?

Vet Anes 2018

Answer 22

Bolus patterns associated with T2
Thread patterns with T1
All T2 needle tips intracanal
All T1 needle tips embedded in bone

Question 23

In Rawlinson’s 2018 study “Evaluation of the equine mental foramen block: cadaveric and in vivo injectate diffusion,” why was the 5ml injectate volume found to be superior?

Vet Anes 2018

Answer 23

The 5ml volume terminated in the caudal canal in 50% (6/12) vs 3ml volume 25% (3/12)

no difference between injectate volumes on distance traveled within canal, diffusion pattern and length of circumferential nerve staining

Question 24

Rawlinson’s 2018 study “Evaluation of the equine mental foramen block: cadaveric and in vivo injectate diffusion,” cites the critical length of nerve exposed to a local anesthetic to reduce or block impulse conduction as how many miilimeters of exposed nerve?

Vet Anes 2018

Answer 24

6 to > 30mm

Question 25

Rawlinson's 2018 study "Evaluation of the equine mental foramen block: cadaveric and in vivo injectate diffusion," suggest that what percent of mental nerve blocks will be effective? ## Footnote Vet Anes 2018

Answer 25

30-60% ## Footnote 30% based on in vivo testing, 60% based on cadaveric testing

Question 26

Rawlinson's 2018 study "Evaluation of the equine mental foramen block: cadaveric and in vivo injectate diffusion," sites that how many nodes of Ranvier must be blocked to achieve anesthesia of myelinated nerves?

Answer 26

3 (internodal length for mammalian fibers ~1mm)

Question 27

In Best's study "A blinded crossover study design to evaluate midazolam as an adjunct for equine standing sedation for routine oral examinations" what was the outcome between the midaz group and placebo group? ## Footnote Best 2024 J Eq Vet Science

Answer 27

There were no significant differences in any of the single or overall sedation scores between treatment groups or within individual horses (P=0.3). ## Footnote Trends towards improvement of some assessed characteristics of sedation, including decreased tongue movement and less resistance to acceptance of speculum were observed.

Question 28

Nervous horses may benefit from which anxiolytic drug prior to dental procedures? A. Tramadol B. Trazodone C. Detomidine D. Ketamine ## Footnote Easley Textbook, ch 23

Answer 28

Trazodone ## Footnote Dose 2.5-10mg/kg orally twice daily. Recommend testing dose a few days prior to procedure Acepromazine is another anxiolytic given IV 20-30 minutes prior to procedure

Question 29

Which of the following are common side effects of alpha-2-agonists? A. Tachycardia, hypotension, decreased GI motility, and polyuria B. Tachycardia, hypertension, decreased GI motility, and anuria C. Bradycardia, hypotension, increased GI motility, and polyuria D. Bradycardia, hypertension, decreased GI motility, and polyuria ## Footnote Easley Textbook, ch 23

Answer 29

D. Bradycardia, hypertension, decreased GI motility, and polyuria

Question 30

What is the duration of the following opioids? Buprenorphine Morphine Butorphanol ## Footnote Easley Textbook, ch 23

Answer 30

Buprenorphine duration is 8-12 hours Morphine duration 4-6 hours Butorphanol duration 30-60 min

Question 31

Lidocaine is commonly used for its analgesic, anti-inflammatory, and antiendotoxaemic properties. However, toxicity is possible; whatis a sign of toxicity and a good indicator lidocaine infusion should be stopped? ## Footnote Easley Textbook, ch 23

Answer 31

Muscle fasciculation

Question 32

What are the following locoregional anaesthetic drug time to onset and durations: Lidocaine Mepivicaine Bupivicaine ## Footnote Easley Textbook, ch 23

Answer 32

Lidocaine - < 2 min, 1-2 hours Mepivicaine - <2 min, 1.5-3 hr Bupivicaine - 5-10 min, 3-8 hours

Question 33

Maxillary nerve block desensitizes which structures? ## Footnote Easley Texbook, ch 23

Answer 33

Ipsilateral maxillary teeth and gingiva, soft tissues rostral to infraorbital foramen, and nasal vestibule +/- lacrimal nerve → lubricate ipsilateral eye every 30 minutes during procedure

Question 34

The infraorbital nerve block desensitizes which structures? ## Footnote Easley Texbook, ch 23

Answer 34

Ipsilateral maxillary teeth and gingiva, soft tissues rostral to infraorbital foramen, and nasal vestibule If only passed slightly into foramen, doesn’t always anaesthetise molars

Question 35

The inferior alveolar nerve block desensitizes which structures? ## Footnote Easley Texbook, ch 23

Answer 35

Ipsilateral mandibular alveolar mucosa, teeth, gingiva, skin and labial mucosa rostral to mental foramen

Question 36

The mental foramen nerve block desensitizes which structures? ## Footnote Easley Textbook, ch 23

Answer 36

ipsilateral alveolar mucosa, incisors and canine teeth, and labial mucosa, skin, and gingiva rostral to mental foramen Mental nerve block desensitizes only the ipsilateral lower lip

Question 37

What are some nerve block complications for the maxillary nerve block? ## Footnote Easley Textbook, ch 23

Answer 37

retrobulbar hematoma, decreased lacrimation of ipsilateral eye

Question 38

What are some nerve block complications for the infraorbital nerve block? ## Footnote Easley Textbook, ch 23

Answer 38

puncture of adjacent blood vessels, abscess

Question 39

What are some nerve block complications for the inferior alveolar nerve block? ## Footnote Easley Textbook, ch 23

Answer 39

lingual anaesthesia, abscess, lingual trauma

Question 40

What are some nerve block complications for the mental nerve block? ## Footnote Easley Textbook, ch 23

Answer 40

abscess, muzzle trauma

Question 41

In McAndrews' study "Evaluation of Three Methods of Sensory Function Testing for the Assessment of Successful Maxillary Nerve Blockade in Horses," what was the success rate of the maxillary nerve blocks? ## Footnote JVD 2023

Answer 41

73% success rate

Question 42

In McAndrews' study "Evaluation of Three Methods of Sensory Function Testing for the Assessment of Successful Maxillary Nerve Blockade in Horses" what nerve stimulation techniques were more reliable? ## Footnote JVD 2023

Answer 42

Needle prick and nostril clamping with a hemostate ## Footnote gingival algometry not as reliable

Question 43

According to Easley 2022 what are the reported advantages of standing sedation over general anesthesia for dental procedures? ## Footnote Chp 23

Answer 43

Decreased surgical hemorrhage increased client compliance improved access to both sides of head reduced frustration with endotracheal tube positioning

Question 44

What is the mechanism of action of trazodone? ## Footnote Easley 2022, chp 23

Answer 44

Serotonin receptor antagonist/reuptake inhibitor anxiolytic drug ## Footnote recommended dosing 2.5-10mg/kg PO q12h

Question 45

What are common cardiac side effects of alpha-2 agonists? ## Footnote Easley 2022, chp 23

Answer 45

Bradycardia (second degree AV block most common bradyarrhythmia) Decreases cardiac output --> initial increase in peripheral vascular resistance leading to hypertension followed by normo to hypotension

Question 46

What are common non-cardiac side effects of alpha-2 agonists? ## Footnote Easley 2022, chp 23

Answer 46

Hyperglycemia polyuria decreased GI motility ataxia

Question 47

What are uncommon possible complications associated with alpha-2 agonists? ## Footnote Easley 2022, Chp 23

Answer 47

Paradoxical aggression --> effects on alpha-1 adrenergic receptors, more common with xylazine followed by detomidine (lower alpha-1: alpha-2 selectivity) Respiratory distress --> occurs in febrile horses sedated with alpha-2s, tachypnea leading to respiratory distress

Question 48

Combining alpha-2 agonists with opioids results in what percent reduction of each drug dose alone? ## Footnote Easley 2022, Chp 23

Answer 48

near 50%

Question 49

What is the duration of action of butorphanol and what side effect is it associated with? ## Footnote Easley 2022

Answer 49

30 minutes to 1 hour Head twitching ## Footnote Marly 2014, Clarke 1991

Question 50

What is the duration of action of morphine and what dose should not be exceeded in a 4 hour period? ## Footnote Easley 2022, Chp 23

Answer 50

duration 4-6 hours 0.2mg/kg over 4 hour period max dose

Question 51

What occurs when morphine is administered IV quickly? ## Footnote Easley 2022, chp 23

Answer 51

Histamine release Excitement ## Footnote should be given slowly

Question 51

What is the onset and duration of buprenorphine? ## Footnote Easley 2022, Chp 23

Answer 51

onset 45-60 minutes for peak effect druation 8-12 hours ## Footnote Provides adequate sedation and analgesia but may have more side effects and postop complications compared to morphine

Question 52

What are the advantages and disadvantages with using midazolam for standing sedation procedure? ## Footnote Easley 2022, Chp 23

Answer 52

Advantages: reduction in chewing activity and tongue movements Disadvantages: significantly more ataxic (likely due to muscle relaxation properties), midazolam alone causes severe excitement

Question 53

What kind of needles are recommended for nerve blocks? ## Footnote Easley 2022, Chp 23

Answer 53

Tuohy --> rounded bevel with offset cutting edges that push vasculature and nerves away from cutting edge

Question 54

In Synder's 2016 study "Effects of buprenorphine added to bupivacaine infraorbital nerve block on isoflurane minimum alveolar concentration using a model for acutre dental/oral surgical pain in dogs," what was the duration of action for the infraorbital nerve blocks? ## Footnote JVD 2016

Answer 54

36-48 hours ## Footnote 1ml of 0.5% bupivacaine with 0.3ml of 0.3mg/ml buprenorphine

Question 55

What can be used to deliver topical anesthetics? ## Footnote Easley 2022, Chp 23

Answer 55

Catheter Laryngo-tracheal mucosal atomizer

Question 56

How far caudal to the point where the facial crest dorsally deviates to become part of the rostral zygomatic arch should the injection site for the extraperiorbital fat body insertion technique (EFBI) be placed? ## Footnote Easley 2022, chp 23

Answer 56

2-3cm

Question 57

In Nannarone's 2016 study "Retrograde maxillary nerve perineural injection: A tomographic and anatomical evaluation of the infraorbital canal and evaluation of the needle type and size in equine cadavers," what was the median infraorbital foramen hieght and width? ## Footnote The Vet J 2016

Answer 57

median height 1.2cm median width 0.6cm ## Footnote infraorbital foramen is ellipitcal shaped

Question 58

In Nannarone's 2016 study "Retrograde maxillary nerve perineural injection: A tomographic and anatomical evaluation of the infraorbital canal and evaluation of the needle type and size in equine cadavers," what was the described shape of infraorbital canal and what was the median length? ## Footnote The Vet J 2016

Answer 58

Serpentine median length 13.6cm

Question 59

In Nannarone's 2016 study "Retrograde maxillary nerve perineural injection: A tomographic and anatomical evaluation of the infraorbital canal and evaluation of the needle type and size in equine cadavers," how was obstruction to passage of a 21 gauge Tuohy needle into the infraorbital canal resolved? ## Footnote The Vet J 2016

Answer 59

Retracting the needle 0.5-1cm and slightly rotating needle when advancing

Question 60

Describe the maxillary nerve block via infraorbital canal technique described by Nannarone in their 2016 paper "Retrograde maxillary nerve perineural injection: A tomographic and anatomical evaluation of the infraorbital canal and evaluation of the needle type and size in equine cadavers." ## Footnote The Vet J 2016

Answer 60

Manual elevation of the levator labii superioris muscle and infraorbital nerve insertion of a 19G x 8cm Tuohy needle with bevel directed laterally along floor of infraorbital foramen with careful rotation until entire needle inserted 10ml injected ## Footnote Quincke needles found to be more difficult to insert (straight sharp tip)

Question 61

In Weber's 2019 study "Ex vivo evaluation of the distribution of a mixture of mepivacaine 2% and iopromide following local infiltration of the infraorbital nerve via the infraorbital foramen," needle insertion how far into the infraorbital canal with what volume of injectate adequately filled the infraorbital canal to the maxillary foramen? ## Footnote Equine Vet Educ 2019.

Answer 61

3cm 10ml

Question 62

In Weber's 2019 study "Ex vivo evaluation of the distribution of a mixture of mepivacaine 2% and iopromide following local infiltration of the infraorbital nerve via the infraorbital foramen," increased retrograde rostral leakage and into the maxillary sinus was greater with what volume of injectate? ## Footnote Equine Vet Educ 2019

Answer 62

15ml ## Footnote tested 15ml vs 10ml inserting both 3cm into canal with 22G 3cm long needle

Question 63

What are the landmarks for finding the infraorbital foramen? ## Footnote Easley 2022. chp 23

Answer 63

line between the nasoincisive notch and point of the facial crest displace the levator nasolabialis muscle and palpate the infraorbital foramen 1-2cm caudal to midpoint of line

Question 64

In Harding's 2012 study "Comparison of two approaches to performing an inferior alveolar nerve block in the horse," what two methods were evaluated, what were the reported success rates for each, and was the difference stat sig? ## Footnote Aust Vet J 2012

Answer 64

Angled vs vertical angled success rate 73% vertical success rate 59% No stat sig difference between the two

Question 65

Henry's 2014 study "Evaluation and clinical use of an intraoral inferior alveolar nerve block in the horse," showed that location of the mandibular foramen can vary up to how many mm from the third molar tooth and how many mm from the ventral border of the mandible? How about from the rostral edge of the ramus? ## Footnote EVJ 2014

Answer 65

59 +/- 7.7mm caudal to third molar tooth 123 +/- 9.4mm from ventral surface of mandible 36 +/- 4.7mm from rostral edge of ramus

Question 66

In Easley's 2022 text, what landmarks are suggested for localizing the mandibular foramen from an extraoral approach? ## Footnote chp 23

Answer 66

line drawn 1cm dorsal to the alveolar crest of the mandibular premolars and a line between the lateral mandibular condyle and the ventral aspect of the mandible where the facial vein is located ## Footnote these modifications eliminate reliance on eye position and dental height which vary with age and breed

Question 67

What the difference between the mental nerve block and the mental foramen block? ## Footnote Easley 2022, chp 23

Answer 67

mental nerve block targets only the mental nerve rostral to the foramen so only desensitizes the ipsilateral lower lip mental foramen block targets the rostral inferior alveolar nerve and mendtal nerves so desensitizes the lower lip and dental structures

Question 68

In Rawlinson's 2018 study "Anatomic analysis of the equine mental foramen and rostral mandibula canal using computed tomography," where was the mental foramen located along the mandible? ## Footnote Vet Anaesth Analg 2018

Answer 68

2/3rd the distance along the incisor-premolar interdental space from the third incisor and 1/3rds the height of the mandible from the dorsal surface of the interdental space

Question 69

In Rawlinson's 2018 study "Anatomic analysis of the equine mental foramen and rostral mandibula canal using computed tomography," what was the mean mental foramen size and what morphological variations were seen? ## Footnote Vet Anaesth Analg 2018

Answer 69

mean size 6.4mm x 5.6mm bifurcated (n=1) and double foramina (n=3) observed

Question 70

In Rawlinson's 2018 study "Anatomic analysis of the equine mental foramen and rostral mandibula canal using computed tomography," what were the mean angles of the mental foramen into the mandibular canal in transverse, sagittal and dorsal planes respectively? ## Footnote Vet Anaesth Analg 2018

Answer 70

transverse: 68 degrees sagittal: 28 degrees dorsal: 41 degrees

Question 71

In Rawlinson's 2018 study "Anatomic analysis of the equine mental foramen and rostral mandibula canal using computed tomography," the rostral mandibular canal was found to have varying levels of circumferential mineralization with what percent of canals having no visible bony walls to the level fo the second premolar? Lack of mineralization was more common in what age of horses? ## Footnote Vet Anaesth Analg 2018

Answer 71

~30% older horses

Question 72

When performing an extraoral mental foramen block, what muscle is retracted dorsally? ## Footnote Easley 2022, chp 23

Answer 72

depressor labii inferioris

Question 73

Cardiac arrest can occur with the maxillary nerve block if the local anesthetic is injected into what structure? ## Footnote Easley 2022, Chp 23

Answer 73

Dural cuff of the optic nerve

Question 74

In Tanner's 2019 study "A Retrospective Study of the Incidence and Management of Complications Associated with Regional Nerve Blocks in Equine Dental Patients" what is the reported incidence of lingual trauma 24 hours post injection for the inferior alveolar nerve block? ## Footnote JVD 2019

Answer 74

4%

Question 75

What is the mortality rate for elective, non-emergency general anesthesia procedures for equine patients as compared to dogs? ## Footnote Easley 2022, chp 23

Answer 75

equine 1% dogs 0.1%

Question 76

What percentage of equine general anesthesia fatalities are associated with recovery and what are the most common causes of fatalities in that peroid? ## Footnote Easley 2022, chp 23.

Answer 76

Over a third fractures and myopathies

Question 77

What inhalants are favored in lengthy dental procedures and why? ## Footnote Easley 2022, chp 23

Answer 77

sevoflurane and desflurane due to their low solubility coefficients --> faster clearance and recovery times

Question 78

What mean arterial pressure should the blood pressure be kept at and above? ## Footnote Easley 2022, chp 23

Answer 78

75mmHg

Question 79

Why should arterial blood gases be evaluated intermittently in horses under GA? ## Footnote Easley 2022, chp 23

Answer 79

Pulse oximetry and capnography may not be very accurate in the horse pulse oximetry tends to underestimate hemoglobin saturation ET-PaCO2 differences can be 15mmHg

Question 80

Overextension of the head can result in what complication? ## Footnote Easley 2022, chp 23

Answer 80

Laryngeal paralysis --> increased risk for upper airway obstruction in recovery

Question 81

In Potter's 2016 study "Preliminary investigation comparing a detomidine continuous rate infusion combined with either morphine or buprenorphine for standing sedation in horses," which treatment group had stat sig higher intraoperative sedation scores? ## Footnote Vet Anaesth Analg 2016

Answer 81

Buprenorphine ## Footnote No differences in ataxia scores, heart rate, or overall adequacy of sedation

Question 82

In Potter's 2016 study "Preliminary investigation comparing a detomidine continuous rate infusion combined with either morphine or buprenorphine for standing sedation in horses," what treatment group had at least one postoperative complication in all cases and which treatment group had no postoperative complications? ## Footnote Vet Anaesth Analg 2016

Answer 82

Buprenorphine all had complications Morphine all had no complications

Question 83

In Stauffer's 2017 paper "Maxillary nerve blocks in horses: an experimental comparison of surface landmark and ultrasound-guided techniques," what were the success rates with surface landmarks, standard ultrasound guidance, and SonixGPS guidance? ## Footnote Vet Anaesth Analg 2017

Answer 83

Surface landmarks 50% Standard ultrasound guidance 65% SonixGPS 83%

Question 84

In Stauffer's 2017 paper "Maxillary nerve blocks in horses: an experimental comparison of surface landmark and ultrasound-guided techniques," what was the overall complication rate and what stat sig differences in complication rates were present? ## Footnote Vet Anaesth Analg 2017

Answer 84

complication rate 54% No sig difference in complication rate found between the three methods

Question 85

In Tanner's 2019 study "A Retrospective Study of the Incidence and Management of Complications Associated with Regional Nerve Blocks in Equine Dental Patients" what nerve block had no reported complications? ## Footnote JVD 2019

Answer 85

infraorbital

Question 86

In Iacopetti's 2015 study "The Inferior Alveolar Nerve of the Horse: Course and Anatomical Relationship with Mandibular Cheek Teeth," in 95% of horses where does the nerve change directions between the mesial root of one tooth and the distal root of another? ## Footnote Anat Histo Embryol 2015

Answer 86

Between the mesial root of M1 and the distal root of PM4

Question 87

In Iacopetti's 2015 study "The Inferior Alveolar Nerve of the Horse: Course and Anatomical Relationship with Mandibular Cheek Teeth," where does the inferior alveolar nerve course relative to the apices of the molar teeth vs the premolar teeth? ## Footnote Anat Histo Embryol 2015

Answer 87

IAN ventral to the apices of the molar teeth PM4: lingual to roots and coronal to the apices PM2, PM3: lingual to roots and in proximity to the apices

Question 88

Which of the following is correct regarding cardiac output? A. Bradycardia diminishes cardiac output by reducing stroke volume B. Tachycardia diminishes cardiac output by reducing stroke volume C. Afterload impedance to cardiac output is a common problem under GA D. Cardiac output determines systemic vasomotor tone ## Footnote Lumb and Jones

Answer 88

B. Tachycardia diminishes cardiac output by reducing stroke volume

Question 89

Stroke volume is determined by what two factors? ## Footnote Lumb and Jones

Answer 89

Preload Myocardial contractility

Question 90

Cardiac output is determined by what two factors? ## Footnote Lumb and Jones

Answer 90

Heart rate Stroke volume

Question 91

What two factors determine blood pressure? ## Footnote Lumb and Jones

Answer 91

Cardiac output Peripheral vasomotor tone

Question 92

What is the important determinant of peripheral tissue perfusion? ## Footnote Lumb and Jones

Answer 92

Peripheral vasomotor tone

Question 93

What is the important determinant of brain and heart perfusion? ## Footnote Lumb and Jones

Answer 93

Arterial blood pressure

Question 94

What two factors determine blood oxygen content? ## Footnote Lumb and Jones

Answer 94

Hemoglobin concentration Oxygenation

Question 95

What two factors determine oxygen delivery? ## Footnote Lumb and Jones

Answer 95

Oxygen content Cardiac output

Question 96

What eyeball positions are associated with light and deep and light-medium to deep-medium anesthetic depth respectively? ## Footnote Lumb and Jones

Answer 96

Light and deep: central light-medium and deep-medium: rotated medioventrally

Question 97

At what heart rate or below should horses be treated for bradycardia? ## Footnote Lumb and Jones

Answer 97

< 25 bpm

Question 98

What are common causes of bradycardia that are not responsive to pharmacological treatment? ## Footnote Lumb and Jones

Answer 98

Severe hypothermia Cardiac conduction abnormalities Severe myocardial hypoxemia

Question 99

What classes of drugs are used to treat bradycardia? ## Footnote Lumb and Jones

Answer 99

anticholinergics sympathomimetics

Question 100

What factors were associated with increased risk of death for horses undergoing acute emergency abdominal surgery? ## Footnote Lumb and Jones

Answer 100

Long duration of anesthesia Hypotension

Question 101

What is the internal diameter of a size 6 endotracheal tube? ## Footnote Lumb and Jones

Answer 101

6mm ## Footnote Tube sizing often reflects the internal diameter of the tube

Question 102

What type of endotracheal tube is most commonly used in large and small animals? ## Footnote Lumb and Jones

Answer 102

cuffed Murphy type tube

Question 103

What is the purpose of the Murphy eye/hole in a Murphy endotracheal tube? ## Footnote Lumb and Jones

Answer 103

To provide an alternative route for gas flow if the beveled opening became occluded

Question 104

What muscles are incised to perform a tracheotomy? ## Footnote Equine Surgery 5th edition.

Answer 104

Cutaneous colli (more superficial) paired sternothyrohyoideus muscles

Question 105

What direction should a tracheotomy incision be made in and what percent of the tracheal circumference should the tracheotomy incision not exceed? ## Footnote Equine Surgery 5th edition

Answer 105

the annular ligament should be incised parallel to the orientation of the rings should not exceed 50% of the tracheal circumference ## Footnote parallel to rings incision prevents postsurgical tracheal collapse and granulation tissue formation

Question 106

Systolic blood pressure is primarily determined by what cardiovascular factors? ## Footnote Lumb and Jones

Answer 106

Stroke volume Arterial system compliance

Question 107

Diastolic pressure is primarily determined by what cardiovascular factors? ## Footnote Lumb and Jones

Answer 107

Vasomotor tone Heart rate

Question 108

How is cardiac preload clinically assessed? ## Footnote Lumb and Jones

Answer 108

End diastolic diameter via echocardiography Diameter of posterior vena cava via chest rads Ease of jugular vein distension

Question 109

In horses what can be used as a surrogate marker of central venous pressure? ## Footnote Lumb and Jones

Answer 109

Jugular venous pressure

Question 110

What is the normal central venous pressure of laterally recumbent vs dorsally recumbent or standing horses? ## Footnote Lumb and Jones

Answer 110

laterally recumbent: 15-20 cmH2O dorsally recumbent or standing: 5-10cmH2)

Question 111

Positive pressure ventilation impedes what cardiovascular factors? ## Footnote Lumb and Jones

Answer 111

Intrathoracic venous return diastolic filling of the heart stroke volume

Question 112

Large and small stroke volumes are associated with what pulse and pulse pressure waveform characteristics? ## Footnote Lumb and Jones

Answer 112

Bounding pulse → tall, wide waveform → likely associated with large stroke volume Thready pulse → short, narrow waveform → small stroke volume

Question 113

What causes hemoglobin concentration to decrease during general anesthesia? ## Footnote Lumb and Jones

Answer 113

Anesthetic induced vaso and splenic dilation Administration of non-hemoglobin containing fluids Intraoperative blood loss

Question 114

Decreased fractional shortening is indicative of what change to contractility? ## Footnote Lumb and Jones

Answer 114

Decreased

Question 115

What causes vasoconstriction? ## Footnote Lumb and Jones

Answer 115

hypovolemia heart failure hypothermia vasoconstrictor drug administration

Question 116

What causes vasodilation? ## Footnote Lumb and Jones

Answer 116

Systemic inflammatory response hyperthermia administration of vasodilator drugs

Question 117

What breathing pattern is described as cycling between hyperventilation and hypoventilation, and may be seen in a healthy anesthetized horse? ## Footnote Lumb and Jones

Answer 117

Cheyne-Stokes breathing

Question 118

Which capnograph indicates that the sample port is too close to fresh gas inflow? ## Footnote Lumb and Jones

Answer 118

c.

Question 119

Which capnograph is indicative of excessive alveolar deadspace (hypovolemia, thromboembolism)? ## Footnote Lumb and Jones

Answer 119

e.)

Question 120

Which capnograph is indicative of deadspace rebreathing? ## Footnote Lumb and Jones

Answer 120

f.)

Question 121

An increased arterial-venous PCO2 gradient suggests what in terms of tissue perfusion? ## Footnote Lumb and Jones

Answer 121

Decreased tissue perfusion

Question 122

How would you troubleshoot the following capnograph?

Answer 122

There is a slant to the upstroke portion of the expiratory phase of the breathing cycle - this may indicate a kinked endotracheal tube, an obstructed endotracheal tube, partial airway obstruction or bronchospasm.

Question 123

How would you troubleshoot the following capnograph? ## Footnote Lumb and Jones

Answer 123

The baseline is not returning to zero, there may be exhausted CO2 absorbing granules, incompetent or absent unidirectional valves, decreased oxygen flow rate in a non-rebreathing circuit, or damaged non-rebreathing circuits.

Question 124

How would you troubleshoot the following capnograph?

Answer 124

There is no plateau or an abnormal downstroke present on inhalation --> check the endotracheal tube cuff!

Question 125

What is the lowest body temperature not associated with detrimental effects? ## Footnote Lumb and Jones

Answer 125

96F

Question 126

What body temperatures can cause ventricular fibrillation? ## Footnote Lumb and Jones

Answer 126

72-74F

Question 127

What body temperatures cause marked CNS depression? ## Footnote Lumb and Jones

Answer 127

82-86F ## Footnote Shivering will not occur → require artificial rewarming Atrial arrhythmias may occur, O2 consumption reduced to 50%, heart rate + cardiac output about 35-40% of normal, arterial blood pressure to about 60%, cerebral metabolism ~25%

Question 128

Cell damage starts at what hyperthermic temperature? ## Footnote Lumb and Jones

Answer 128

108F ## Footnote Oxygen delivery can no longer keep up with incr metabolism and O2 consumption

Question 129

What is the difference between a tranquilizer and a sedative? ## Footnote Lumb and Jones

Answer 129

Tranquilizers induce a feeling of calm but do not reduce overall response to external stimuli like a sedative

Question 130

Phenothiazines work on what receptors? ## Footnote Lumb and Jones

Answer 130

Adrenergic Muscarinic Dopaminergic Serotonergic Histamine

Question 131

What is the mechanism of action for the sedative effects of phenothiazines? ## Footnote Lumb and Jones

Answer 131

dopamine receptor (D2) blockage

Question 132

Acepromazine (sedative) 0.1mg/kg IV decreases mean aortic pressure and cardiac output by what percents respectively? ## Footnote Lumb and Jones

Answer 132

aortic pressure 20-30% Cardiac output 10-15%

Question 133

What is the mechanism of action of benzodiazepines? ## Footnote Lumb and Jones

Answer 133

Ehance GABA receptor's affinity for GABA ## Footnote increased chloride conductance and hyperpolarization of postsynaptic cell membranes. (alpha1 and alpha 2 subunits)

Question 134

What is the mechanism of action for alpha-2 agonists? ## Footnote Lumb and Jones

Answer 134

binding receptors in the nociceptive pathways in the brainstem and dorsal horn of the spinal cord afferent input modulated and reduces norepinephrine release (presynaptic inhibition) and occupancy of those receptors (postsynaptic inhibition)

Question 135

What is the mechanism of action for bradycardia by alpha 2 adrenergic receptor agonists? ## Footnote Lumb and Jones

Answer 135

Increased systemic vascular resistance Reduced central symphathetic outflow

Question 136

What is the onset and duration of action of xylazine? ## Footnote Lumb and Jones

Answer 136

Onset 5-10 minutes Duration 30-60 minutes

Question 137

What is the onset and duration of detomidine? ## Footnote Lumb and Jones

Answer 137

onset 5 minutes duration 1 hour

Question 138

How does the onset to peak sedation and duration of romifidine compare to xylazine and detomidine? ## Footnote Lumb and Jones

Answer 138

longer onset and duration (15 minutes to peak sedation)

Question 139

What adrenergic receptor antagonists are typically used for dexmedetomidine and xylazine respectively? ## Footnote Lumb and Jones

Answer 139

Dexmedetomidine: atipamezole Xylazine: yohimbine, tolazine

Question 140

What is the definition of potency? ## Footnote Lumb and Jones

Answer 140

the relative dose needed to elicit a response ## Footnote Not related to duration of effect or efficacy

Question 141

What is first pass metabolism? ## Footnote Lumb and Jones

Answer 141

The intestinal lining and liver biotransform a portion of the medication into a form that is not systemically effective

Question 142

Systemic opioid doses are most effective at decreasing nociception of which nerve fibers?

Answer 142

C fibers (slow conducting, unmyelinated nerves associated with dull aching pain) ## Footnote less effective on A delta fibers (fast conducting, myelinated nerves associated with sharp, discrete pain)

Question 143

Opioids tend to cause what change to pupil diameter in horses and cats? ## Footnote Lumb and Jones

Answer 143

Mydriasis

Question 144

Morphine and butorphanol tend to impair coordination of motility of what parts of the gastrointestinal tract specifically? ## Footnote Lumb and Jones

Answer 144

Morphine: colon Butorphanol: jejunum

Question 145

What opioid receptors ehance urine production? ## Footnote Lumb and Jones

Answer 145

kappa

Question 146

What is the mechanism of action for urine retention with opioid use? ## Footnote Lumb and Jones

Answer 146

Decrease in detrusor muscle contraction Increased tone of urinary sphincters Inhibition of micturition

Question 147

Cats and horses tend to experience what thermoregulation response to opioid use? ## Footnote Lumb and Jones

Answer 147

Hyperthermia

Question 148

Which opioid is effective as an NMDA antagonist? ## Footnote Lumb and Jones

Answer 148

Methadone ## Footnote more effective analgesic for chronic and refractory pain

Question 149

What opioid has reported hyperesthesia, muscle fasciculations, sweating and adverse CV effects reported in horses? ## Footnote Lumb and Jones

Answer 149

Meperidine (pethidine)

Question 150

Buprenorphine is how many times more potent than morphine? ## Footnote Lumb and Jones

Answer 150

25 times

Question 151

What is the IV onset to action of buprenorphine and the duration of action? ## Footnote Lumb and Jones

Answer 151

20 minutes 4-12 hours (dependent on route)

Question 152

Oral transmucosal route of buprenorphine is effective in what species? ## Footnote Lumb and Jones

Answer 152

Dogs and cats not horses

Question 153

What opioid receptors does butorphanol act on? ## Footnote Lumb and Jones

Answer 153

Mu antagonist to partial mu agonist kappa agonist

Question 154

Naloxone works primarily on what opioid receptors? ## Footnote Lumb and Jones

Answer 154

mu antagonist

Question 155

What is dantrolene used to treat? ## Footnote Lumb and Jones

Answer 155

Malignant hyperthermia Rhabdomyalosis

Question 156

What are the general effects of guaifenesin? ## Footnote Lumb and Jones

Answer 156

Centrally acting skeletal muscle relaxant with sedative properties Co-administered with anesthetic agents for induction and maintenance of general anesthesia

Question 157

What are the properties/effects of methocarbamol? ## Footnote Lumb and Jones

Answer 157

centrally acting muscle relaxant that selectively inhibits spinal and supraspinal polysynaptic reflexes through its action on interneurons without direct effects on skeletal muscle

Question 158

What is the molecular mechanism of action of local anesthetics? ## Footnote Lumb and Jones

Answer 158

Primary ion channel blockers Blockade of inward sodium currents through voltage gated sodium channels which impedes membrane depolarization and nerve excitation and conduction ## Footnote Also block voltage dependent potassium and calcium channels act on intracellular G-protein coupled receptors

Question 159

What percent of sodium conductance at 3 or more nodes of Ranvier of a myelinated nerve fiber must be blocked to achieve local anesthesia? ## Footnote Lumb and Jones

Answer 159

> 84%

Question 160

What is the chemical structure of lidocaine, mepivacaine and bupivacaine? ## Footnote Lumb and Jones

Answer 160

amino-amides ## Footnote metabolized by the liver

Question 161

What effects have been shown when alpha-2 adrenergic receptor agonists are added to local anesthetics? ## Footnote Lumb and Jones

Answer 161

Shorter onset longer duration of sensory and motor block enhanced block quality, lower pain scores, decreased systemic opioid requirement

Question 162

What are the signs and results of cardiac toxicity secondary to local anesthetics? ## Footnote Lumb and Jones

Answer 162

Prolonged PR and QRS intervals, hypotension, bradycardia, respiratory arrest, asystole

Question 163

What is allodynia? ## Footnote Lumb and Jones

Answer 163

Pain due to a stimulus which does not normally provoke pain.

Question 164

What is the only class of analgesic drugs that prevent nociception transmission? ## Footnote Lumb and Jones

Answer 164

Local anesthetics

Question 165

Does COX1 or COX2 act centrally? ## Footnote Lumb and Jones

Answer 165

COX1- antinociceptive effects at level of the brain, spinal cord

Question 166

Which classes of analgesics prevent generation of noxious stimuli?

Answer 166

Local anesthetics NSAIDs ## Footnote Opioids modulate pain by increasing the pain threshold but do not prevent generation of noxious stimul

Question 167

What arrhythmia does high dose dobutamine cause?

Answer 167

Ventricular tachycardia

Question 168

What are the reported complication after maxillary nerve block? ## Footnote Easley ch 29

Answer 168

Retrobulbar hematoma Globe prolapse Horner’s signs

Question 169

Laceration of the tongue can be a complication of which nerve block? ## Footnote Easley ch 29

Answer 169

Inferior alveolar

Question 170

What are possible causes of this ETCO2 waveform? ## Footnote Equine Anesthesia, Hubbel, ch 8

Answer 170

Question 171

What are the possible causes of this ETCO2 waveform? ## Footnote Equine Anesthesia, Hubbel, ch 8

Answer 171

Question 172

What possible causes are there for this ETCO2 waveform? ## Footnote Equine Anesthesia, Hubbel, ch 8

Answer 172

Question 173

What causes are there for this waveform ETCO2? ## Footnote Equine Anesthesia, Hubbel, ch 8

Answer 173

Question 174

Name this ECG ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 174

Sinus arrhythmia

Question 175

Name this ECG ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 175

Sinus tachycardia. Note the shortening of the P wave, PR, and QT intervals; the depression of the PR segment; and the elevation of the ST-T wave—all of which are physiologic changes observed with tachycardia.

Question 176

Name this ECG ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 176

2nd degree AV block (p waves without QRS) ## Footnote Common in horses sedated with alpha-2s

Question 177

Name this ECG ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 177

Sinus arrest - give atropine to restore

Question 178

What are the ECGs in A and B ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 178

A. Atrial tachycardia B. Atrial flutter ## Footnote A - Regular abnormal P waves (P’) are evident through- out the strip, with many superimposed on the QRS and T complexes. Most of ectopic P waves are blocked in the AV node and are not conducted to the ventricles. B - Atrial activity is characterized by saw-toothed flutter waves (F) occurring at a rapid rate and regular intervals.

Question 179

Name this ECG ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 179

Ventricular tachycardia

Question 180

What can cause this ECG reading? ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 180

Hyperkalemia produced atrial standstill, a ventricular conduction disturbance (wide QRS), and ST-T abnormalities

Question 181

How does the choice in inotropic drugs dopamine and dobutamine differ? ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 181

Dopamine is preferred for treating bradycardia and hypotension Dobutamine is preferred for treating hypotension without bradycardia ## Footnote Both used for bradycardia!

Question 182

What are side effects of dobutamine? ## Footnote Equine Anesthesia, Hubbel, ch 3

Answer 182

Dose-dependent effects Vasoconstriction Tachycardia Ventricular arrhythmias

Question 183

How does hematocrit differ in donkeys compared to horses? ## Footnote Equine Anesthesia, Hubbel, ch 18 (Nora Matthews)

Answer 183

Donkeys are adapted to the desert; increases in hematocrit, commonly seen with dehydration in horses, do not occur until donkeys are approximately 30% dehydrated

Question 184

What condition are donkeys predisposed to when anorexic? ## Footnote Equine Anesthesia, Hubbel, ch 18 (Nora Matthews)

Answer 184

Hyperlipidemia

Question 185

How does the jugular vein differ in donkeys to horses when trying to get venous access? ## Footnote Equine Anesthesia, Hubbel, ch 18 (Nora Matthews)

Answer 185

Cutaneous colli muscle is a sheet of fascia, and the skin is thicker ## Footnote Needles should be angled more perpendicular to the skin in donkeys

Question 186

How does the facial artery differ in donkeys? ## Footnote Equine Anesthesia, Hubbel, ch 18 (Nora Matthews)

Answer 186

the anatomy of the branches of the facial artery (i.e., the artery that is located under the temporal crest) makes it difficult to place an arterial catheter in that location

Question 187

How do vitals differ in donkeys compared to horses? ## Footnote Equine Anesthesia, Hubbel, ch 18 (Nora Matthews)

Answer 187

HR response to exercise/pain the same Body temp may increase higher in donkeys in warm climates or exercise Resp rates higher in donkeys - 20 to 30 breaths/min is normal at rest ## Footnote HR most reliable to indicate pain in a donkey as they are so stoic

Question 188

How does sedative dosing differ for mules and donkeys? ## Footnote Equine Anesthesia, Hubbel, ch 18 (Nora Matthews)

Answer 188

same drugs as horses mules require 50% more drug than donkeys or horses to achieve adequate sedation Ketamine after sedation with an a2-agonist is generally acceptable but is metabolized more rapidly in donkeys and mules than in horses ## Footnote ketamine - Faster metabolism in conjunction with a more rapid distribution phase results in higher doses and more frequent readministration

Question 189

How shoud your combination for GKX differ for donkeys? ## Footnote Equine Anesthesia, Hubbel, ch 18 (Nora Matthews)

Answer 189

Increase the concentration of ketamine - 2 g/L rather than 1g/L in the horse

Question 190

what nerves innervate the TMJ, and what block(s) should be performed for a condylectomy? ## Footnote Sanders EVE 2014

Answer 190

branches of maxillary (zygomaticotemporal and zygomaticofacial) and the mandibular (auriculotemporal) nerves Perform both ipsilateral maxillary and mandibular nerve blocks ## Footnote Facilitated a standing condylectomy in this case report

Question 191

What is the genetic defect of concern with HYPP? And how prevalent is it? ## Footnote Doherty, Manual of Equine Anesthesia and Analgesia

Answer 191

Defect in NA-K pump Excess Na --> Increased serum K+ Less negative resting potential --> triggered more (why muscle fasciculations are 1st sign) 0.4% American QH; 2% registered QH

Question 192

What clinical signs during anesthesia would make you susptect HYPP? ## Footnote Doherty, Manual of Equine Anesthesia and Analgesia

Answer 192

Prolonged recovery = #1 Muscle fasciculations ECG changes: inc amplitude T wave, wide QRS, dec amplitude P wave) Tachycardia --> bradycardia Hyperthermia

Question 193

What muscle is being lifted here in Rice's JVD step by step? ## Footnote JVD 2017

Answer 193

levator labii superioris muscle ## Footnote Different than muscle listed in Ch 23 of Easley 2022!