Equine anaesthesia Flashcards
What pre-med is commonly used in horses
ACP
Alpha2 agonist and opiate IV
When might we avoid using ACP in equine anaesthesia
In shock colic cases due to already being vasodilated
Which opiate do we usually use in equine pre-meds and when might we change this
Usually butorphanol; this has more of a sedative effect rather than pain relief
If very painful can use morphine (but generally don’t use this due to risk of ileus)
How much sedation do we use for pre-med for GA compared with for standing sedation procedures
Double
What do we use at induction in equine GA
Ketamine IV
Also add in midazolam to counteract the muscle rigidity caused by ketamine
Methods of induction
Free fall
Assisted 1 person
Crush with/without door
Flop
How do we encourage a horse to fall during assisted one person induction
Hold the head up; pull on head and push on shoulder to direct them to fall away from you
How do we maintain anaesthesia in the field
Ketamine top ups every 10 minutes using one third to half of an induction dose
Can add more alpha 2 agonist if this starts to wear off
How do we maintain anaesthesia in the hospital
Using isoflourane
Circle breathing system
Monitoring anaesthesia in the field under ketamine maintenance
Difficult since ketamine causes dissociation
Animals can look relatively awake with central eye, blink, irregular breathing and nystagmus
Increased muscle tone may indicate lightening plane
How to monitor anaesthesia plane under isoflourane
Want eyes to be medial NOT central
If nystagmus is seen, this means the animal is very light
Increasing blood pressure is a better indicator of lightening plane vs HR/RR
What is the aim of blood pressure maintenance during equine GA
Keep MAP over 70mmHG to avoid underperfucion of muscles and spinal cord leadin to ataxia
General rule for how long recovery should take
20 mins + extra 20 mins for every hour under anaesthesia
What transition occurs when tube is removed and how can we try and make sure this is safe
From tube breathing to obligate nasal breathing
Involves movement of soft palate back into position; via swallowing
So remove the tube once the horse can swallow
What neuropathies might we see following equine GA and how can we avoid this
Radial nerve compression of lower leg when lying in lateral; should pull lower leg as far forward as possible
Facial nerve neuropathy from buckles on head collar
What is spinal cord malacia
Complication of GA sometimes seen in young large heavy breed horses when lying directly on back
Key sign on recovery = dog sitting
= complete paralysis from lumbar area down
What factors increase the risk of fractures during recovery
Myopathy
Underlying stress fractures in race horses
Peri-parturient mares at higher risk
What recumbency should we recover horses in
If operation done in lateral then recover them in same recumency as op done to avoid compressing the only non-collapsed lung
