Field Anesthetic Flashcards
How long can IV anesthesia safely be used for in a horse?
1 hour
For a PLANNED surgery, what is the safest duration?
<3 hours
T/F: the risk of mortality under anesthesia is extremely high
F, there is a risk but it really shouldn’t be a barrier to colic sx, etc.
T/F: you can anesthetize an excited horse
F, they’ll wake up excited you should wait till they calm down
What arrhythmias are common with field anesthesia?
1st and 2nd degree AV blocks
Atrial fibrillation
If a horse has a history of HYPP or tying up what should you ensure before anesthesia?
Make sure they’re heavily sedated so they don’t tie up from excitement right before
what are the 3 types of commonly used standing sedation and premedication?
- Alphas 2 agonists
- Phenothiazines
- Opioids
Describe Alpha 2 Agonists uses, administration and side effects
Xylazine and Detomidine are usually given IM or IV but can also be PO if needed. These provide muscle relaxation, sedation and analgesia which cause the horse to have a 5 point stance when peak effects occur and is a reversible drug. Its important to note these drugs decrease heart rate and CO so you may see first or second degree AV blocks. These drugs also decrease GI motility and increase urination.
t/f: detomidine and xylazine provide comparable sedation but xylazine is more potent
F, the sedation is comparable but detomidine is more potent than xylazine
how long does it take for alpha 2s to take effect?
IV: 3-5 minutes
IM: 10-15 minutes
when might you use a detomidine CRI?
for standing sedation in cases of lacerations, laser surgery, and thoracoscopy, etc. Be careful because this may cause a secondary AV block and bradycardia (turn down if this occurs)
Describe phenothiazines effects, administration and side effects
Acepromazine can be given PO, IV, or IM and results in a calm horse that can still be aroused. Its considered a tranquilizer and provide no analgesia with minimal muscle relaxation or ataxia. This drug does have the potential for hypotension and priaprism.
T/F: acepromazine is usually combined with an alpha 2 to enhance sedation
T
what is the onset time and duration for acepromazine?
onset of 15-30 minutes and duration of 6-10 hours so its good if you want them to be sedate for a bit
Describe opiods effects and general use in horses.
Opiods in horses are used adjectively with tranquilizers because alone they may cause excitement. Compared to small animals butorphanol provides better analgesia in horses. Morphine or fentanyl should be used for very painful procedures and fentanyl absorption is much faster than in small animals.
how long is ketamine/alpha 2 anesthesia?
15 - 20 minutes with rapid induction
how should you administer xylazine and ketamine for anesthesia?
both can be given IV but you should give xylazine and then follow it with ketamine
what are possible issues with xylazine/ketamine anesthesia?
- the muscle relaxation can be poor (could add diazepam)
- apneustic breathing is common
- only for minor surgeries
T/F: Telazol with xylazine has a smooth recovery always
F, theres potential for prolonged/rough recoveries
why might you give telazol/xyalzine instead of ketamine/xylazine?
longer duration of anesthesia
explain the benefits and uses of TKD in anesthesia of horses
This combination provides a light pain of anesthesia that induces recumbency in about 1 minute while using lower doses of all of the drugs. The horse will then be sternal in 36 minutes and standing in 40 minutes but this should not be used along for surgery.
guaifenesin
a really good centrally acting muscle relaxant but no unconsciousness or analgesia. It can help reduce the amount of other drugs needed
Signs of guaifenesin overdose
extension of forelimbs
labored breathing
respiratory and cardiac arrest
what role do benzodiazepenes have in anesthesia?
diazepam and midazolam provide additional muscle relaxation in conjunction with other agents
propofol
expensive to use in horses but may combine with GG or ketamine to decrease dose, overall not as useful in the field bc of respiratory depression
what options do you have to maintain anesthesia in the field?
Use longer acting drugs or repeating administration of short-acting drugs. Can give repeated boluses or set up a CRI
describe triple drip (aka GKX) anesthesia
This can be used for induction in foals and can be used to induce/maintain anesthesia for up to 1 hour. The drugs should be delivered by a large bore catheter and supplemental oxygen provided. The signs of overdose similar to light place of anesthesia. The recovery is influenced by total dose administered.
TIVA
Total intravenous anesthesia
how are all TIVA anesthetics delivered?
to effect
what are the AVCAA guidelines for monitoring anesthesia procedures <1 hours?
cardiovascular: digital pulse palpation, CRT and mm color
respiratory: observation of respiratory rate and rhythm, the respiratory rate gets more rapid and forceful as the horse gets lighter
t/f: healthy horses can tolerate hypoxia for short periods
T, recumbent horses will be slightly hypoxic and if needed oxygen can be supplemented during field surgery for compromised patients
T/F: balanced analgesia can extend field anesthesia
T
when do most surgical injuries occur ?
induction and recovery when the horse tries to stand early
