LA Sedation Flashcards
what drug classes have use as sedatives in LA?
-anticholinergics only in emergencies
-phenothiazines
-alpha2 agonists
-benzodiazepines
-opioids
-others, typically given as IV induction agents
when might we use anticholinergics in LA?
only in emergencies
when can we use benzodiazepines in LA?
only in foals or small ruminants as a sedative
what type of opioids are most commonly used in LA
kappa-agonists - butorphanol
what LAs can we use propofol for?
foals, calves, small ruminants only
5 alpha2-agonists
-xylazine
-detomidine
-romifidine
-medetomidine
-dexmedetomidine
alpha2-agonist reversal agents
yohimbine, tolazoline, atipamezole
species sensitivity from least to most for alpha2 agonists
swine < horse < llama < sheep < cow < goat
(least = higher doses to most = lower doses)
alpha2 agonist advantages
¡ Reliable dose dependent sedation
> IV (IM or PO)
¡ Analgesia
¡ Muscle relaxation
¡ Reversible
¡ Not scheduled
alpha2 agonist disadvantages
¡ Cardiovascular effects
¡ Upper airway relaxation (equine snoring)
¡ Ileus (equine)
¡ Diuresis (all)
¡ Increased uterine tone (cows late term ?)
¡ Hypoxemia potential in ruminants
¡ Aggression (xylazine equine)
alpha2 agonist disadvantages
¡ Cardiovascular effects
¡ Upper airway relaxation (equine snoring)
¡ Ileus (equine)
¡ Diuresis (all)
¡ Increased uterine tone (cows late term ?)
¡ Hypoxemia potential in ruminants
¡ Aggression (xylazine equine)
alpha2 agonist resp effects in horses
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
what resp effect is possible in ruminants given alpha2 agonists?
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
alpha2 agonist contraindications in LA
¡ Debilitated - shock
¡ Hypoxemic
¡ Hypovolemic without stabilization
¡ Urinary Obstruction
¡ 3rd Trimester of Pregnancy in cattle
xylazine is the most common alpha2 agonist used in what species?
ruminants
difference in xylazine dose for ruminant vs horse
¡1/10th dose for maximal sedation compared to a horse
÷High end dose will induce recumbency in ruminants; not in horses
withdrawl time for xylazine
48 hrs milk
3 days meat
when and how do we reverse an a2 agonist?
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
acepromazine advantages:
tranquilization, sedation, anxiolysis
¡ Good tranquilization in horses
-Anti-arrhythmic
-IV; IM; or oral possible
-Not scheduled
acepromazine disadvantages:
¡ 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
withdrawl time for acepromazine
¡ 48 hrs milk ; 7 days meat
3 opioids used in LA and the receptors they work on:
Morphine: Mu agonist
Butorphanol: Kappa agonist-Mu antagonist
Buprenorphine: partial Mu agonist
what is morphine commonly used for in LA? Major side effect? Other consideratoins?
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
what is butorphanol most used for in LA? side effect?
Kappa Agonist-Mu Antagonist
Used in equine and ruminant
analgesia (?)
Adds to ataxia
what is buprenorphine most used for in LA? side effect?
Partial Mu Agonist
¡ Used in equine
¡ Some reduction in GI motility
¡ Some excitement reported
Benzodiazepines – Diazepam & Midazolam disadvantages:
-Poor sedation in adult horse
-Concern for ataxia at dose required for sedation
-Muscle relaxation
-Generally given with ketamine as anesthetic induction in equine
benzodiazepines advantages:
Good sedative without negative side effects
-Young or adult small ruminants
-Calves or foals < 2 weeks of age
benzodiazepines routes of admin:
Diazepam only IV
Midazolam IV or IM
is diazepam commonly used for adult bovines? why?
Not routinely used as sedative in adult bovine
¡ Minimal calming
¡ Same concern for recumbency
diazepam withdrawl
¡ 30 days meat
¡ DO NOT use in lactating animals
commonly used sedative combinations in LA:
Alpha2-Agonists & Opioids
¡ Xylazine/morphine / butorphanol / buprenorphine
Alpha2-Agonist & Acepromazine
¡ Xylazine and acepromazine
¡ Detomidine and acepromazine
¡ Romifidine and acepromazine
considerations for alpha2 agonist and opioid combination
-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
