Written Exam - Ruminant Anesthesia Flashcards by Madeleine Swindell

what are signalment-related concerns for anesthesia in goats?

extremely old or young, obesity, & poor BCS

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what is the most common cardiac abnormality in sheep/goats?

ventricular septal defect

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what is representative of healthy baseline bloodwork of a ruminant prior to anesthesia?

PCV - 22-36%, TP: 6.0-7.5 g/dL

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what are the baseline vital parameters for ruminants?

temp: 101.5-103.5

hr: 70-80 bpm

rr: 12-24 bpm

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what are the big 5 concerns for animals going under anesthesia? (5 H’s)

hypotension
hypoxemia
hypoventilation
hypothermia/hyperthermia
+/- hypoglycemia

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in order of most sensitive to anesthetic drugs to least, list the species affected

goats > cattle > sheep > llamas > alpacas > horses

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what drug is linked with causing macrophage-associated pulmonary edema in sheep?

alpha 2 agonists

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why must caution be used when anesthetizing ruminants with alpha-2s?

alpha-2s cause cardiovascular/pulmonary dysfunction

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what animals are most sensitive to alpha-2s?

goats

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what is the maximum total bolus dose of lidocaine in kids?

7mg/kg

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what dose range of lidocaine do we see seizure activity?

10mg/kg

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what species are very sensitive to lidocaine?

goats

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what is the order of clinical signs seen in lidocaine toxicity?

GI > neuro > cardiac

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why do we need to fast ruminants prior to anesthesia?

most will regurgitate/salivate - fast 12-18 hours prior

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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

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what are your treatment options for ruminant gi bloating during surgery?

change position
pass orogastric tube
trocharize with a large bore needle

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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

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what is the best positioning for ruminants during surgery?

sternal is best - left lateral is second best

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what is the best way to monitor ventilation during surgery?

capnography

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what is a normal capnograph measurement for goats under anesthesia?

35-45 mmHg

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what things can cause respiratory depression in goats under anesthesia?

anesthetic drugs, inhalants, and PaCO2

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if you see a shark fin wave on capnograph, what do you think is happening?

obstruction or bronchospasm

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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?

1. hypoventilation - typical problem 2. V/Q mismatch 3. diffusion impairment 4. shunt 5. low FiO2

what are the 4 types of hypoxia?

1. hypoxemia 2. anemia 3. stagnant 4. 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?

1. hypovolemia 2. lack of contractility 3. vasodilation 4. 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?

1. hemorrhage 2. pain 3. 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?

1. brain - opioids & alpha 2s 2. dorsal horn - local anesthetics, opioids, & alpha 2s 3. peripheral nerves - local anesthetics 4. 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?

1. myopathy 2. neuropathy 3. regurgitation 4. excessive bloat 5. 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