Alpha 2 agonists clinical application

Question 1

Dexmedetomindine as premedication

Answer 1

-alpha agonist for small animals; good for healthy exotics
-highly selective for alpha 2 receptors

Question 2

Dexmedetomindine dosing (premed)

Answer 2

-always combine with an opioid

-decrease dose by half if given IV

Question 3

Dexmedetomidine as dose dependent cardiovascular and resp depression (premed)

Answer 3

Choose dose based on:
-patient temperament
-hydration status
-anticipated pain level of procedure

Question 4

Dexmedetomidine timing (premed)

Answer 4

Onset of action= 15 mins

Duration of action: 45mins-1hr

Question 5

Reversal for dexmedetomidine

Answer 5

Reversal available= Atipamezole

Question 6

Xylazine as premed

Answer 6

-used for large animals (horses, ruminants, camelids)
-excellent sedation
-reflex bradycardia profound by transient

Question 7

Xylazine timing as premed

Answer 7

Onset of action: mins

Duration of action: 30-45 mins

RARELY reversed

Question 8

Detomidine as premed

Answer 8

-used mainly in horses
-good quality sedation but may be slightly ataxic/depressed than when using xylazine

Question 9

Detomidine timing

Answer 9

*similar to xylazine

Onset of action: mins

Duration of action: 30-45 mins

RARELY reversed

Question 10

Dexmedetomidine for minor procedures

Answer 10

-used in small animals for minor procedures such as quill removal, laceration repair

-sedation more profound if given IV (top ups through catheter)

-combine with opioid to improve sedation AND/OR local block if needed

Question 11

Xylazine for standing procedures

Answer 11

-good for field procedures for cows and horses

Question 12

Horse xylazine use for standing procedures

Answer 12

-teeth floats, minor lacerations
-feet firmly planted but can still kick

-often combine with butorphanol

Question 13

Cow xylazine use for standing procedures

Answer 13

-foot trims

-will result in recumbency in 15mins; duration is 60mins

-combine with butorphanol; reverse with tolazoline

Question 14

Detomidine use for stnading procedures

Answer 14

-excellent sedation for standing procedures

-often combine with opioid

-for long procedures (laparoscopic ovariectomy, rectovaginal fistula), make infusion and administer to effect

Question 15

Dexmedetomidine use during surgery

Answer 15

-used for anesthetic sparing and analgesia
-used in dogs and hrses; not commonly used in cats
-more effective with opioid infusion
-be aware of bradycardia with bolus

Question 16

Dexmedetomidine infusion post-operatively

Answer 16

-Pros: analgesia and sedation

-Indications:
-anxious dogs who need to be kept calm
-fractious dogs need to be in ICU for post operative care and handling
-painful dogs that need something more than opioid

Question 17

Addition of dexmedetomidine to local anesthetic

Answer 17

Prolongs duration of block
-use same syringe with mixture
-use small amount
-dilute dexmedetomidine concentration
-some systemic uptake= increased levels of sedation

Question 18

Mechanism of action of dexmedetomidine and local anesthetic

Answer 18

Vasoconstriction associated with alpha 2 agonist delays clearance of local anesthetic from the site

Question 19

Drugs used in epidurals of small animals

Answer 19

1. dexmedetomidine +bupivacaine (no analgesic improvement, but did prolong motor function)
2. Bupivacaine + morphine
3. Bupivacaine alone

**direct neurotrophic effects not tested; dexmedetomidine not routinely used in small animals

Question 20

Epidural use in large animals

Answer 20

-use dexmedetomidine
-prolongs duration of blockade
-easily accessible for practitioners
-does not produce motor blockade
-often combined with local anesthetics and opioids

Question 21

Effects of epidurals in large animals

Answer 21

-produce analgesia- action on receptors in the substantia gelatinosa of the dorsal horn of spinal cord
-adverse effects (ataxia, recumbency)
-systemic absorption does occur

Question 22

Epidurals in horses

Answer 22

Can use xylazine, detomidine, romifidine

Question 23

Xylazine epidurals in horses

Answer 23

-Optimal dose=0.17 mg.kg; 1/5th of dose given systemically for horse sedation
-dilute in 10ml of 0.9% saline or lidocaine for injection
**Do not exceed 10ml if using lidocaine
-provide 25 hrs of perineal analgesia
-no hind limb ataxia
-

Question 24

Detomidine epidurals in horses

Answer 24

-potent analgesic and sedative effects
-results in sedation, ataxia, recumbency, CV effects
-use low doses (20-40 mcg/kg)
-dilute in 10ml of 0.9% saline
-analgesia will spread cranially to T14

-duration of analgesia is shorter than xylazine (2hrs)

Question 25

Detomidine and diuresis in horse epidurals

Answer 25

Detomidine can cause diuresis to occur so is contraindicated in a horse with urinary obstruction

Question 26

Romifidine epidurals in horses

Answer 26

-dose (80 mcg/kg) diluted in 8ml saline
-analgesia inconsistent (can be up to 4hrs)
-spreads cranially similar to detomidine

-effects: sedation, bradycardia, decreased RR

Question 27

Epidural drugs for cattle

Answer 27

-Xylazine

-Xylazine with lidocaine

-Romifidine

Question 28

Xylazine epidurals in cattle alone

Answer 28

-onset of action= 10 mins
-duration=3-4hrs

-diluted in saline

Question 29

Xylazine combined with lidocaine epidurals in cattle

Answer 29

onset of action=5 mins

duration of action=6hrs

Question 30

Side effects of xylazine use in cattle epidurals

Answer 30

-mild to moderate sedation
-mild ataxia
-decreased ruminal motility
-bradycardia

Question 31

Romifidine epidurals in cattle

Answer 31

diluted in saline
-analgesia and sedative effect was dose dependent in intensity and duration of action

Question 32

Blocked cat considerations

Answer 32

-muscle relaxation may aid in passage of urethral catheter

Question 33

Diabetic implications

Answer 33

-reduced insulin leads to an increased hepatic glycogenolysis and gluconeogensis causing hyperglycemia

Question 34

Brachycephalic and animals with laryngeal paralysis considerations

Answer 34

-pharyngeal and laryngeal muscle relaxation may further impair compromised airway
-decreased esophageal sphincter tone= increased risk of regurgitation