Equine Field Anesthesia Flashcards
What should you consider when doing field anesthesia?
- procedural considerations
- environmental considerations
- patient considerations
- equipment (basics, oxygen)
- personnel considerations
what is triple drip?
guaifenesin, ketamine, & xylazine
what are the procedural considerations when doing field anesthesia?
- what is the nature of the injury?
- standing sedation & local block OR GA?
- what is the complexity of the surgery?
- what is the expected duration of the procedure? (top ups; triple drip)
only SIMPLE PROCEDURES of SHORT DURATION should be attempted away from the “relative safety” of the well-equipped & well-staffed hospital
what are the environmental considerations when doing field anesthesia?
- optimal conditions include soft ground & flat/gentle gradient
- avoid man-made or natural hazards: barbed wire fences, farm equipment, ponds, streams, ravines
what are the patient considerations when doing field anesthesia?
- thorough hx & physical exam (cardiovascular & respiratory systems, gut motility, pain)
- stabilization (hemorrhage, fasting)
- weight estimation (drug dosages require an accurate weight)
- owner consent
How do you estimate a Eq weight in the field?
weight tape & calculate
What should be included in the minimum anesthesia equipment for field anesthesia?
- IV catheters
- sufficient amount of drugs
- soft ropes w/ an appropriate halter
- small towel (covering/protecting eyes)
- E-tank w/ nasal insufflation (full tank holds 625 L of oxygen)
- Eq are v prone to hypoxemia during GA (V/Q mismatch)
what are the personnel considerations when doing field anesthesia?
- you are not only responsible for the safety of the horse but also the safety of the owner & every other individual involved
What to use for sedation/premedication in a Eq?
- acepromazine
- A2 agonists
Acepromazine in Eq field anesthesia?
- IV/IM
- may be useful as a “pre-med” often in combo w/ other drugs
- can be used alone for non-painful procedures
- provides anti-arrhythmic effect
- sufficient time should be allowed for it to work (30-40 MINS)
- vasodilation & hypotension does occur (A1 antagonism)
- penile prolapse (should be avoided in breeding stallions)
What is important about A2 agonists in equine field anesthesia?
Xylazine, Detomidine, Romifidine
- provide more reliable sedation
- also provide analgesia & muscle relaxation, some ataxia
- equipotent doses of the 3 different A2 agonists used in Eq
- STANDING SEDATION (use low dose) & PRE-ANESTHETIC MEDICATION (usually use high dose)
What are the cardiovascular effects of IV administration of an A2 agonist in equine field anesthesia?
- bradycardia does not require atropine in Eq or Ru
- wait a few minutes & HR will increase
What is important about A2 agonist drugs & their combinations for sedation in equine field anesthesia?
- A2 agonists used ALONE (DO NOT TRUST - Eq can still kick)
- A2 agonists w/ OPIOIDS: BUTORPHANOL (IV); morphine (use a longer lasting A2 agonist); can mix drugs OR give drugs seperately
- A2 agonists w/ OPIOIDS & ACEPROMAZINE (IV): DETOMIDINE + BUTORPHANOL + ACEPROMAZINE MIX IS COMMON; detomidine + acepromazine is good for mares; romifidine mixed w/ acepromazine = precipitation (DO NOT administer)
What are the steps in induction of anesthesia in equine field anesthesia?
- pre-anesthetic preparation: fast 12 hrs (minimum fast 6 hrs prior to surgery); water until 1 hr before; medical history; physical exam; clinical hematology as necessary
- assess facilities/enviro
- place an IV catheter
- check halter & ropes
- protect facial nerve if leaving halter on the head
- select site (brief the help on safety & potential problems)
What are the common anesthetic field induction protocols?
- xylazine OR detomidine (IV): WAIT A FEW MINS FOR PEAK SEDATION
- Diazepam + Ketamine (mix)
- diazepam is optional but does “smooth” induction
- butorphanol (IV) can be added (often wait until Eq is induced to minimize the potential for excitement)
- consider local anesthetic techniques
