Lecture 14 10/29/24

Question 1

What are the indications for chemical restraint in horses?

Answer 1

-standing surgery
–skin laceration repair
–enucleation
–ovariectomy
–sinusotomy
-diagnostics
–endoscopy
–radiography

Question 2

What are the benefits of using chemical restraint in horses?

Answer 2

-lower risk of complications
-lower cost
-less time

Question 3

What are the disadvantages of using chemical restraint in horses?

Answer 3

-danger to animal
-danger to personnel
-less than ideal surgical conditions
-insufficient analgesia

Question 4

What are the characteristics of the ideal chemical restraint agent?

Answer 4

-small volume
-water soluble
-non-irritant to tissues
-no pain on injection
-rapid onset of action
-non-toxic
-absence of adverse effects
-compatible with other agents

Question 5

What is the preferred approach to chemical restraint?

Answer 5

combination of drugs/multimodal approach

Question 6

Which components of history and physical exam are important to consider for anesthesia?

Answer 6

-age
-size and body condition
-drug sensitivities
-concurrent diseases

Question 7

What are the characteristics of anesthetic drug administration?

Answer 7

-typically given IV
-IV drugs given slowly
-complications if drugs are given perivascular or intra-arterial
-IM possible, but lower bioavailability and slower onset of action

Question 8

What are the cardiovascular effects of acepromazine?

Answer 8

-minimal affects on cardiac output and heart rate
-hypotension
-anti-arrhythmic

Question 9

What are the pros of using acepromazine in horses?

Answer 9

-widely available
-muscle relaxation
-small volume
-augments opioid sedation
-few adverse effects
-inexpensive

Question 10

What are the cons of using acepromazine in horses?

Answer 10

-no analgesia
-slow onset of action
-sedation may persist for several hours
-inconsistency in sedative response
-penile protrusion

Question 11

What are the effects of opioids on the cardiovascular system?

Answer 11

-bradycardia
-hypotension

Question 12

What are the effects of opioids on the CNS?

Answer 12

-analgesia
-sedation
-possible excitement

Question 13

What are the effects of opioids on the resp. system?

Answer 13

-resp. depression
-decreased sensitivity of resp. center to CO2
-hypoventilation

Question 14

What are the effects of opioids on the GI tract?

Answer 14

non-propulsive intestinal motility/ileus with high doses

Question 15

What are the clinical uses of opioids?

Answer 15

-provide sedation with alpha2 agonists for standing restraint
-premedication prior to general anesthesia
-epidural analgesia

Question 16

What are the characteristics of benzodiazepine use in horses?

Answer 16

-mainly for co-induction with ketamine
-minimal CV and resp. side effects
-muscle relaxation
-sedation in foals
-anticonvulsants

Question 17

What are the pros of alpha2 adrenoceptor agonist use in horses?

Answer 17

-dose-dependent sedation, analgesia, and muscle relaxation
-reversible

Question 18

What are the cons of alpha2 adrenoceptor agonist use in horses?

Answer 18

-cardiac and resp. depression
-sedated animal may react to noise/stimuli
-causes ileus
-metabolic effects; diuresis, hypoinsulinemia, hyperglycemia, sweating

Question 19

What are the characteristics of clinical sedation with alpha2 adrenoceptors?

Answer 19

-head lowers
-ataxia; more severe with detomidine and xylazine
-degree and duration of sedation is dose and drug dependent; romifidine > detomidine > xylazine

Question 20

What are the signs of detomidine sedation?

Answer 20

-lowering of the head
-drooping of lip
-relaxation of penis
-base-wide stance

Question 21

What are the delivery methods for standing sedation drug combinations?

Answer 21

-single injection
-infusion

Question 22

What are the characteristics of combining alpha2 agonists with opioids?

Answer 22

-more reliable sedation than alpha2 alone
-less likelihood of sudden reaction to stimuli
-give alpha2 agonist first to sedate, then opioid
-dose adjustments may be needed

Question 23

What are the characteristics of alpha2 reversal?

Answer 23

-cardiorespiratory compromise can occur with alpha2 overdose
-reverse to shorten the prolonged sedation of high dose alpha2s
-reverse the GI effects of alpha2s

Question 24

Why are local/regional blockades used?

Answer 24

increase the efficacy of standing sedation

Question 25

Which local blocks are used in horses?

Answer 25

-line-field
-nerve
-regional/epidural

Question 26

Which nerve blocks are used around the eye?

Answer 26

-auriculopalpebral (eyelid)
-supraorbital

Question 27

Which vertebrae are used as landmarks when given an epidural?

Answer 27

coccygeal 1 and coccygeal 2

Question 28

Why are epidurals given between the coccygeal vertebrae?

Answer 28

to prevent blockage of the femoral nerve and allow the horse to remain standing