Written Exam - Ruminant Anesthesia Flashcards
what are signalment-related concerns for anesthesia in goats?
extremely old or young, obesity, & poor BCS
what is the most common cardiac abnormality in sheep/goats?
ventricular septal defect
what is representative of healthy baseline bloodwork of a ruminant prior to anesthesia?
PCV - 22-36%, TP: 6.0-7.5 g/dL
what are the baseline vital parameters for ruminants?
temp: 101.5-103.5
hr: 70-80 bpm
rr: 12-24 bpm
what are the big 5 concerns for animals going under anesthesia? (5 H’s)
- hypotension
- hypoxemia
- hypoventilation
- hypothermia/hyperthermia
- +/- hypoglycemia
in order of most sensitive to anesthetic drugs to least, list the species affected
goats > cattle > sheep > llamas > alpacas > horses
what drug is linked with causing macrophage-associated pulmonary edema in sheep?
alpha 2 agonists
why must caution be used when anesthetizing ruminants with alpha-2s?
alpha-2s cause cardiovascular/pulmonary dysfunction
what animals are most sensitive to alpha-2s?
goats
what is the maximum total bolus dose of lidocaine in kids?
7mg/kg
what dose range of lidocaine do we see seizure activity?
10mg/kg
what species are very sensitive to lidocaine?
goats
what is the order of clinical signs seen in lidocaine toxicity?
GI > neuro > cardiac
why do we need to fast ruminants prior to anesthesia?
most will regurgitate/salivate - fast 12-18 hours prior
how should ruminant heads be positioned in surgery?
nose needs to be lower than the larynx - properly inflated ETT tube & partially deflate it to extubate
what are your treatment options for ruminant gi bloating during surgery?
- change position
- pass orogastric tube
- trocharize with a large bore needle
why is ruminant gi bloating an emergency during surgery? what clinical signs may be seen?
can lead to severe hypoxemia
may see hypoventilation, hypercapnia, & decreased CV return to the heart
what is the best positioning for ruminants during surgery?
sternal is best - left lateral is second best
what is the best way to monitor ventilation during surgery?
capnography
what is a normal capnograph measurement for goats under anesthesia?
35-45 mmHg
what things can cause respiratory depression in goats under anesthesia?
anesthetic drugs, inhalants, and PaCO2
if you see a shark fin wave on capnograph, what do you think is happening?
obstruction or bronchospasm
T/F: respiration can be affected by positioning of the animal
true - animals in dorsal recumbency have a harder time
what is hypoxemia?
PaO2 < 60mmHg & SpO2 < 90%
what is the gold standard for monitoring hypoxemia?
arterial blood gas - use median artery or auricular artery
what does pulse oximetry measue?
saturated hemoglobin
what are the 5 types of hypoxemia?
- hypoventilation - typical problem
- V/Q mismatch
- diffusion impairment
- shunt
- low FiO2
what are the 4 types of hypoxia?
- hypoxemia
- anemia
- stagnant
- histotoxic
what are the average measurements of blood pressure in ruminants under anesthesia?
SAP: 90-130 mmHg
MAP: 70-110 mmHg
DAP: 60-90 mmHg
what is the absolute cut-off of blood pressure in goats for MAP?
65 mmHg
what are the 4 general causes of hypotension?
- hypovolemia
- lack of contractility
- vasodilation
- arrhythmia
what do you do if you have a hypotensive animal due to hypovolemia?
fluid bolus
what do you do if you have a hypotensive animal due to a lack of contractility?
give a positive inotrope
what do you do if you have a hypotensive animal due to vasodilation?
give epinephrine
what do you do if you have a hypotensive animal due to arrhythmias?
anti-arrhythmic medications
what happens if you give too much fluid to a hypotensive animal that wasn’t hypovolemic?
increased risk of pulmonary/peripheral edema & hemodilution (electrolyte abnormalities & reduced oncotic pressure)
what does a fluid bolus test help with?
determines if your animal is hypotensive due to hypovolemia - if pressure increases transiently, animal likely needs volume
if on positive pressure ventilation - may see improvement in plethysmograph waveform (SpO2 wave)
what are some procedure-related considerations for ruminants undergoing anesthesia?
- hemorrhage
- pain
- positioning - neuropraxia, rhabdomyolysis
what is the blood volume of a goat?
~8% of body weight - 80ml/kg
what is the transfusion trigger?
will vary from animal to animal - consider at 15-20% blood loss in a healthy animal
what are some signs of pain in an animal under anesthesia?
tachycardia, bucking the ventilator, tachypnea, increased blood pressure, & emergence/movement
where along the nociceptive pathway can anti-nociception be provided?
- brain - opioids & alpha 2s
- dorsal horn - local anesthetics, opioids, & alpha 2s
- peripheral nerves - local anesthetics
- peripheral nociceptors - local anesthetics & anti-inflammatory drugs
what is infiltration in regards to a local block?
subcutaneous injection of small volumes of local anesthetics into tissues - diffusion into surrounding tissues anesthetizing nerve fibers & endings
what nerves are blocked in a proximal paravertebral nerve block?
T13, L1, & L2
what are the advantages of a proximal paravertebral block?
small dose required
wide & uniform area of analgesia & muscle relaxation
absence of local anesthetic at surgical site
what are the disadvantages of a proximal paravertebral block?
scoliosis of the spine - causes difficulty when closing
landmarks are harder to find in obese/heavily muscled animals
requires more skill
potential for epidural administration
major vessels pose a risk
what are the advantages of a distal paravertebral block?
lack of scoliosis
easier to perform
more consistent results
minimal ataxia
what are the disadvantages of a distal paravertebral block?
larger doses required
variations in efficiency due to variations in anatomy
what landmarks are used for a distal paravertebral block?
L1, L2, & L4 - blocking T13, L1, L2, & L3 spinal nerves
what are the landmarks used for a lumbosacral epidural?
dorsal spinous process of L6 in ruminants or L7 in dogs/cats & S1 medial crest
what are the landmarks for a sacrococcygeal epidural?
either at S5-Co1 or Co1-Co2 - tail is elevated to identify where the tail hinges
T/F: an intratesticular block doesn’t block the scrotum
true
what 5 things should be considered when positioning an animal for surgery?
- myopathy
- neuropathy
- regurgitation
- excessive bloat
- trauma to the eye
what is the MAC for sheep & goats?
sheep: 1.58%
goats: 1.2-1.5%
what are the disadvantages when trying to assess depth in ruminants under anesthesia?
their eye position is unreliable
they lose the palpebral reflex very early on in anesthesia
should retain corneal at all times - other reflexes intact
