Equine Anesthesia Flashcards
anesthestic risk of mortality increased in:
repair with internal fixation (screws and plates)
last 1/3 of pregnancy
laparotomy (colic surgery)
Sx >4hrs
>1 month or <12 years of age
T/F premedication with acepromazine was associated with reduced risk of anesthetic death
True
what are the 2 common causes of anesthetic death
cardiac arrest and post-operative collapse
fractures and myopathies
according to Dugdale et al. what was the biggest cause of anesthetic related mortality in horses
fractures and dislocations
risk increased during recovery
what are common procedures that can be performed in a standing horse
dental/sinus procedures
laparoscopy
epidural anaesthesia/analgesia
wounds closures
what are some advantages of standing anesthesia
cheaper, faster and less risk to horse
what is the normal heart rate for a horse
20-45 bts/min
what is the most common arrhythmia in fit horses
2° AV block (mobitz type I)
What respiratory disease is common in horses over 10yrs, housed indoors?
COPD
crackles and wheezes, medical tx prior to anesthesia, +/- bronchodilators
3 methods for obtaining a weight
weighbridge
tape
estimate
T/F horses should be given tetanus toxoid, antibiotics and NSAIDs pre-op
True
T/F picking out feet +/- remove shoes, rinse mouth, and grooming are all part of the pre-op preparation
True
T/F never anesthetize an unsedate horse
True
indications for Acepromazine as a pre-med
provides tranquilization
cardioprotective
reduce risk of anesthetic mortality
contraindications of acepromazine
hypovolemic - colic
young foals
breeding stallions - priapism
what is a mainstay premed in adult horses
alpha 2 agonists
IV, IM, transmucosally, SQ
what are some signs of sedation
head down
droopy lips
sleepy
wide-based stance
what are the side effects of opioids in horses
decreased GI motility
when are benzodiazepines used
tranquilisation of foals (1-2months of age)
few CV and resp effects
what is the aim for induction
quiet environment
controlled
slow
gentle
Ketamine - slower effect, tend to sit back
main options for induction
free fall/assisted
swing gate
tilt table
sling
T/F for orthopedic conditions, the affected leg should be positioned away from the wall
True
why is propofol not typically used
large volume of drug needed
cost
T/F telazol gives good induction after alpha 2 premed but the recovery is poor
True
T/F intubation is usually performed blindly
True
how do you intubate horses
gag helpful to open mouth
extend neck
need to go in midline
dislocate epiglottis from soft palate
advantages of TIVA vs inhalant
no special requirement
used in field or OR
minimal CV/resp depression
lower M&M
pollution risk low
disadvantages of TIVA vs inhalant
all drugs need to be metabolized
some have active metabolites
max duration 2 hrs
not easy to control anaesthetic depth
what does TIVA consist of
GG (muscle relaxant)
alpha 2 agonist
ketamine
which ECG lead configuration should be used
base-apex
lead 1
which arteries are used for arterial blood pressure
facial
transverse facial
digital
ideal MAP
>70 mmHg
what does arteria blood pressure provide information about
perfusion
what does pulse ox measure?
hemoglobin saturation
what is the minimum acceptible value for pulse ox
90%
advantages of pulse ox
quick and easy to apply
non-invasive
continuous
what does respiratory gas monitoring include
PaCO2
PaO2
ETAA
Resp. rate
how can depth of anesthesia be assessed
eye position - one eye central, one rotated back or forward; slow palpebral reflex, lacrimation
anal tone
no limb movement
no swallowing
no nystagmus
problems during equine anesthesia
hypotension
hypoventilation
hypoxemia
recovery - myopathy, neuropathy, spinal cord malacia, recovery quality
how can you treat hypotension under anesthesia
reduce vaporizer setting
increase rate of fluid administration
use vasoactive drugs
what is the main cause of hypoxemia
V:Q mismatch
relate to shape of horses diaphragm, position during anesthesia
how do you prevent/treat hypoxemia
increased FiO2
mechanical ventilation
use of beta 2 agonist
change position (head up)
reduce pressure from abdominal contents (starve pre-op)
prevention of myopathy
monitor arterial pressure and maintain (minimum MAP of 70 mmHg)
prevention of myopath and neuropathy
padding
positioning - lateral lower limb pulled forward, limbs parallel to ground, remove head collar
causes of post operative myopathy
muscle ischemia and inadequate perfusion
MAP <70 mmHg
hypoxemia
vasconstriction
prolonged anesthesia (>2 hrs)
larger horses
compartment syndrome
problems in recovery
excitement/disorientation (fractures, abrasions)
post anaesthetic myopathy
respiratory obstruction
neuropathic paralysis
haemorrhagic myelopathy
T/F longer recovery, shorter and less invasive surgery = better recovery
true
types of recovery
unassisted
manually assisted - head and tail ropes
felating air pillow
large animal vertical lift
sling recovery
pool recovery
T/F donkies metabolize some drugs more rapidly than horses
True
NSAIDs - require more frequent dosing
T/F donkies more stoical and tolerant of intervention than horses and may be suitable for standing procedures
True
donkies are more/less sensitive to alpha 2 agonist
more
donkies metabolise ketamine more/less rapidly and are more/less sensitive to guaifensin than horses
More
how does intubation differ in donkies vs horses
anatomically different
more difficult due to angle of larynx
may need endoscope
T/F blood pressure is a more sensitive indicator of anesthetic depth in donkies than in horses
True
donkey recovery
slower and more control than horses
less need to sedate
rise like cattle - hind end first
