Field Anesthesia and Chemical Restraint Flashcards
T/F: recumbency is required for short surgical procedures
true
IV anesthesia can be safely used for up to ____ hr.
1
Mortality rate in horses undergoing anesthesia is higher. What are the 4 contributing factors?
- age (foals, older)
- duration of surgery (>3 hr risky)
- drugs used for sedation
- inhalants
Preanesthetics MUST induce …
a state of calmness
You should NEVER anesthetize an excited horse!! If you’ve given pre-sedation and the horse is still excited, then give something else prior to induction/anesthesia.
Pre-anesthetic physical examination should focus on what 2 body systems and why?
respiratory and cardiovascular.
This is because 1) subclinical respiratory disease can become overt after anesthesia and 2) You should ensure you are aware of any arrhythmias and murmurs (and ensure HR is >20)
How long should horses be fasted prior to undergoing anesthesia?
4-6 hours for adults
some surgeries require 24-48 hr (ex. laporoscopic cryptorchid)
What are 3 commonly used drug groups for standing sedation and premedication?
- alpha-2 agonists (xylazine, detomidine)
- phenothiazines (ace)
- opioids
Which of the following statements is FALSE about alpha-2 agonists?
A. they can be administered PO, IM, or IV
B. they produce sedation, muscle relaxation, and analgesia
C. they increase HR and CO which can lead to first and second degree AV blocks
D. peak effect is in 3-5 min (IV) or 10-15 min (IM)
E. they can decrease GI motility
F. they increase urination
G. they are reversible
C. they increase HR and CO which can lead to first and second degree AV blocks
they DECREASE heart rate and cardiac output, which can lead to 1st and 2nd degree AV blocks
How do you know when a horse is adequately sedated with pre-meds?
they assume the 5-point stance
head is down, eyelids and lips are droopy
T/F: detomidine is more potent than xylazine and therefore is a better drug
false – it is more potent, but it is not necessarily a “better” drug. Higher potency simply means that less is required to achieve the same effects.
what are the reversal agents for alpha-2 agonists?
- yohimbine
- atipamazole/ antisedan
- tolazoline
Detomidine can be given orally in applesauce, molasses, or alone but it takes ______ to take effect.
45 min
Which of the following statements is FALSE about a phenothiazine (acepromazine) as a pre-medication?
A. it can be given PO, IV, or IM
B. it produces a calming, relaxing effect, but horse can still be rousable
C. can create hypotension
D. onset is 5-10 minutes, duration is 6-10 hours
E. it produces very minimal muscle relaxation or ataxia
F. it does not provide analgesia
G. when combined with alpha-2 agonist, can enhance sedation
D. onset is 5-10 minutes, duration is 6-10 hours
onset is actually 15-30 minutes, duration is 6-10 hrs
Why are opioids (butorphanol, morphine, TD fentanyl) used in conjunction with tranquilizers such as xylazine?
When opiods are given alone, they can cause excitement.
Why are dissociatives like ketamine used as induction agents in horses?
their onset is rapid and the induction and recovery are very smooth if used with alpha-2’s (xylazine, detomidine)
T/F: ketamine should only be given IV
true
T/F: you should combine xylazine and ketamine in the same syringe when using them in conjunction for induction
false
give xylazine first, then ketamine.
Which of the following statements is TRUE about the xylazine + ketamine combination?
A. good muscle relaxation is achieved
B. tachypnea is common but resolves within the first 5 minutes
C. Adding diazepam provides smoother induction and greater muscle relaxation
D. major surgeries can be performed with this combo alone
C. Adding diazepam provides smoother induction and greater muscle relaxation
A is false because ket + xylazine alone has poor muscle relaxation
B is false because ket + xylazine can actually cause apneustic breathing
D is false because only minor surgeries should be performed with this combo
When using telazol (tiletamine/zolazepam) + xylazine, why are the recoveries “rough” or prolonged?
How could you improve this?
The xylazine is already gone and they are recovering off of the dissociative.
To improve that, you can used detomidine + telazol because detomidine lasts longer than xylazine.
what is the BEST / smoothest drug protocol for laying a horse down in the field?
xylazine + ketamine
T/F: TKD will induce recumbency in 1 minute and the animal will be back standing in 40 minutes. The combination is ideal because it requires less of each drug. However, this combo should not be used alone for surgery.
true
What are the benefits / purpose of use of Guaifenesin?
GG is a muscle relaxant.
It does not induce unconsciousness or analgesia and should not be used alone.
BUT, it allows for other drug amounts to be decreased.
What are the signs of GG overdose?
- extension of forelimbs
- labored breathing
- respiratory and cardiac arrest
it looks like the horse is “getting light”
What is the purpose of adding diazepam or midazolam into your anesthetic protocol?
provides additional muscle relaxation in conjunction with other agents.
It should NEVER be used alone.
