LA Sedation

Question 1

what drug classes have use as sedatives in LA?

Answer 1

-anticholinergics only in emergencies
-phenothiazines
-alpha2 agonists
-benzodiazepines
-opioids
-others, typically given as IV induction agents

Question 2

when might we use anticholinergics in LA?

Answer 2

only in emergencies

Question 3

when can we use benzodiazepines in LA?

Answer 3

only in foals or small ruminants as a sedative

Question 4

what type of opioids are most commonly used in LA

Answer 4

kappa-agonists - butorphanol

Question 5

what LAs can we use propofol for?

Answer 5

foals, calves, small ruminants only

Question 6

5 alpha2-agonists

Answer 6

-xylazine
-detomidine
-romifidine
-medetomidine
-dexmedetomidine

Question 7

alpha2-agonist reversal agents

Answer 7

yohimbine, tolazoline, atipamezole

Question 8

species sensitivity from least to most for alpha2 agonists

Answer 8

swine < horse < llama < sheep < cow < goat
(least = higher doses to most = lower doses)

Question 9

alpha2 agonist advantages

Answer 9

¡ Reliable dose dependent sedation
> IV (IM or PO)
¡ Analgesia
¡ Muscle relaxation
¡ Reversible
¡ Not scheduled

Question 10

alpha2 agonist disadvantages

Answer 10

¡ Cardiovascular effects
¡ Upper airway relaxation (equine snoring)
¡ Ileus (equine)
¡ Diuresis (all)
¡ Increased uterine tone (cows late term ?)
¡ Hypoxemia potential in ruminants
¡ Aggression (xylazine equine)

Question 11

alpha2 agonist disadvantages

Answer 11

¡ Cardiovascular effects
¡ Upper airway relaxation (equine snoring)
¡ Ileus (equine)
¡ Diuresis (all)
¡ Increased uterine tone (cows late term ?)
¡ Hypoxemia potential in ruminants
¡ Aggression (xylazine equine)

Question 12

alpha2 agonist resp effects in horses

Answer 12

Horses – standing sedation – head goes down
¡ Increased resistance and work of breathing
÷ Reversed by elevating head and neck……
¡ Decreased abduction of left arytenoid cartilage
÷ Impact on the recurrent laryngeal neuropathy grade

Question 13

what resp effect is possible in ruminants given alpha2 agonists?

Answer 13

Ruminants potential for hypoxemia

1.When animal becomes recumbent with higher doses
÷ And bloated they cannot ventilate as well
2. Pulmonary intravascular macrophage degranulation – PIMS response
¢ Degranulation results in inflammatory cascade – edema
÷ More common in small ruminants

Question 14

alpha2 agonist contraindications in LA

Answer 14

¡ Debilitated - shock
¡ Hypoxemic
¡ Hypovolemic without stabilization
¡ Urinary Obstruction
¡ 3rd Trimester of Pregnancy in cattle

Question 15

xylazine is the most common alpha2 agonist used in what species?

Answer 15

ruminants

Question 16

difference in xylazine dose for ruminant vs horse

Answer 16

¡1/10th dose for maximal sedation compared to a horse
÷High end dose will induce recumbency in ruminants; not in horses

Question 17

withdrawl time for xylazine

Answer 17

48 hrs milk
3 days meat

Question 18

when and how do we reverse an a2 agonist?

Answer 18

Alpha2-Antagonists
-Yohimbine,Tolazaline, Atipamezole
¡ Reversal has rare indications in the horse

¡ Reversal more common in ruminants
¡ Likely given with swine

¡ Necessary when:
÷Cardio-respiratory compromise
÷Inadvertant overdose
÷To reverse high dose effects
÷To shorten duration of maximal effect

Question 19

acepromazine advantages:

Answer 19

tranquilization, sedation, anxiolysis
¡ Good tranquilization in horses

-Anti-arrhythmic
-IV; IM; or oral possible —
-Not scheduled

Question 20

acepromazine disadvantages:

Answer 20

¡ Penile injury
÷ CAREFUL IN STALLIONS

¡ No analgesia
¡ Longer time to onset even if IV
¡ Hypotension

-Less reliable sedation in adult ruminant
-Increases regurgitation in ruminants during GA or if become recumbent with sedation

Question 21

withdrawl time for acepromazine

Answer 21

¡ 48 hrs milk ; 7 days meat

Question 22

3 opioids used in LA and the receptors they work on:

Answer 22

Morphine: Mu agonist
Butorphanol: Kappa agonist-Mu antagonist
Buprenorphine: partial Mu agonist

Question 23

what is morphine commonly used for in LA? Major side effect? Other consideratoins?

Answer 23

Mu agonist
¡ Used in equine
¡ Major side effects is reduced GI motility
¡ Potential for excitement without a sedative
÷ Weaving more common vs. excitement
¡ Less clinical data in ruminants

Question 24

what is butorphanol most used for in LA? side effect?

Answer 24

Kappa Agonist-Mu Antagonist
Used in equine and ruminant
analgesia (?)
Adds to ataxia

Question 25

what is buprenorphine most used for in LA? side effect?

Answer 25

—Partial Mu Agonist
¡ Used in equine
¡ Some reduction in GI motility
¡ Some excitement reported

Question 26

Benzodiazepines – Diazepam & Midazolam disadvantages:

Answer 26

-Poor sedation in adult horse
-Concern for ataxia at dose required for sedation —
-Muscle relaxation
—
-Generally given with ketamine as anesthetic induction in equine

Question 27

benzodiazepines advantages:

Answer 27

Good sedative without negative side effects
-Young or adult small ruminants
-Calves or foals < 2 weeks of age

Question 28

benzodiazepines routes of admin:

Answer 28

Diazepam only IV
Midazolam IV or IM

Question 29

is diazepam commonly used for adult bovines? why?

Answer 29

Not routinely used as sedative in adult bovine
¡ Minimal calming
¡ Same concern for recumbency

Question 30

diazepam withdrawl

Answer 30

¡ 30 days meat
¡ DO NOT use in lactating animals

Question 31

commonly used sedative combinations in LA:

Answer 31

Alpha2-Agonists & Opioids
¡ Xylazine/morphine / butorphanol / buprenorphine

Alpha2-Agonist & Acepromazine
¡ Xylazine and acepromazine
¡ Detomidine and acepromazine
¡ Romifidine and acepromazine

Question 32

considerations for alpha2 agonist and opioid combination

Answer 32

-Xylazine/morphine / butorphanol / buprenorphine
-greater sedation with neurolepto-analgesia if excitement
-Consider > degree of ataxia in equine
- Consider off label and withdrawal’s in ruminant with opioid