large animal anesthesia Flashcards
3 settings in which large animal anesthesia is performed
field - outside, keep clean, strictly IV no gas
clinic - stall or housed area, aseptic or sterile technique
hospital - complete surgery suite, sterile technique
concerns when anesthetizing ruminants
- drug withdrawal times
- not ideal for general anesthesia
- not economical
- regurgitation and inhalation
- weight of abdominal organs
recommendations for withholding food and water and other preparations prior to anesthesia in horses, cattle, and pigs
horses- 12-24 hrs fast, jug catheter
cattle- 24 hrs fast, jug catheter
pigs - overnight
water access still allowed
pre-anesthetic BW, get weight
anticholinergics
- treat bradycardia
- horse - dec intestinal activity, ileus, colic
- ruminants - dec saliva, more viscous, difficult to clear from trachea, more frequent and higher dosing
alpha 2 agonists
- good sedation
- delayed anesthesia
- bradycardia
- horses can still kick
- 1/10th of dose in ruminants vs horses
- detomidine for horses
phenothiazine
- slower sedative than alpha-2
- good for anxious horses
- synergistic effect with alpha-2
- needle shy horse: combine w detomidine and give sublingually
opioids
- good for short duration visceral analgesia
- fast onset
- combined with alpha-2
- less predictable in ruminants
benzodiazepine
- muscle relaxant
- no analgesia
- fast onset
- premed in neonates
- induction agent when combined with ketamine
neuromuscular blockers
- triple drip
- not manufactured commercially
- must have been compounded
dissociative
- induction
- no muscle relaxation
- give alpha-2 as premed, combine midazolam/diazepam or guaifenesin
inhalant anesthetic
more pronounced hypotension, hypoventilation, reduced co in ruminants
horse intubation
- sternal or lateral
- mouth gag
- blind intubation with palpation
manual reflexes used in assessing anesthetic depth
palpebral, corneal, eye position, ear twitch
TPR for horses
35-50 bpm (>60, <30)
6-12 rpm
98-101 F
TPR for cattle
50-80 bpm
20-30 rpm
100-103 F
how do respirations differ in cattle compared to horses
prone to bloating causing shallow respirations (rapid)
common locations for obtaining a pulse on a horse
submandibular
facial
radial
lateral
metatarsal
digital
methods of obtaining blood pressure in horses
- indirect cuff: base of tail, peripheral limb
- indirect doppler
- direct with 12-16 g catheter
normal equine BP
40-70 mmHg
75-100 mmHg
90-120 mmHg
equine anesthesia safety
- protect eye
- open grassy area
- large stall without feeders or buckets
equine anesthesia recovery
- rope on halter or tail
- remain recumbent
- apply pressure or sit on dorsal aspect of neck
- plan an exit
equine behavior under anesthesia
- may hold breath up to 2 minutes
- have strong flight instinct
post anesthetic myelopathy
- hypoperfusion of compressed muscle
- dependent muscles when in lateral or dorsal
- draft breeds more prone
- unable to stand
- pain on standing
concerns when anesthetizing equine neonates
- minimize CV depression
- foals lay down when tired
- do not fast
- mare should remain with foal if possible
- hold down until awake
