Equine Anesthesia Flashcards

1
Q

What side effect should you be cautions of if using acepromazine in horses?

A

Penile prolapse

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2
Q

____________ can cause abortion in the third trimester of pregnancy

A

Xylazine

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3
Q

What are common prodecures requiring anesthesia in equines?

A

Colic
Arthroscopy
Castration
Upper airway dz (tie-back, ethmoid hematoma, guttural pouch mycosis)

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4
Q

What are the basics you should asses in your clinical exam before an anesthetic procedure?

A

History

Heart rate
Respiratory rate
Mucous membrane (colour and CRT)
Hydration status

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5
Q

What are the basic lab test that should be run prior to anesthesia?

A

Basic hematology and biochem
PCV
TSP
Urine SG

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6
Q

What site is usually used for venous catherizaiton in horses?

A

Jaguar

—aseptic prep and local anesthetic infiltration

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7
Q

What catheter size should be used in an adult horse

A

12g

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8
Q

How should you prepare a horse for anesthesia?

A

Starve for 4-6 hours
Withhold water for 2 hours

Pull out all shoes
Rinse out mouth

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9
Q

T/F: a2 agonsits can cause potent sedation with some analgesic effects?

A

True

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10
Q

Which of the following is the most potent a2 agonist?

Xylazine
Detomidine
Romifidine

A

Detomidine

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11
Q

What opioid is most commonly used as an analgesic in horse and when would it be contraindicated?

A

Butorphanol

Contraindicated in severe pain

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12
Q

What premedication can reduce GI mobility and predispose a horse to colic?

A

Opioids and a2 agonsits

They are still be best options for sedation/analgesia in horse

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13
Q

What premedicaitons can provide analgesia in horse?

A
A2-agonists 
Fluxinine megulmine 
Meloxicam 
Butorphanol 
Methadone/morphine
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14
Q

When should you administer the muscle relaxant?

A

Before induction agent

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15
Q

What are muscle relaxants used in horses?

A

GGE = glyceryl guaicolate ether

Benzodiazepine: diazepam or midazolam

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16
Q

What agents are used for induction in horse?

A

Ketamine

Thiopentone

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17
Q

What diameter tube is used in intubation of horse?

A

26mm or an average 50kg horse

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18
Q

How should a horse be positions on the theatre table

A

Cushion on pressure points (head, shoulder, pelvis, and limbs)

Stretch limbs apart -> encourage venous return

Protect eyes from trauma

Only in one lateral recumbency!

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19
Q

What type of circuit do you use for equine anesthesia ?

A

Circle, rebreathing

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20
Q

What is the o2 flow rate for induction and maintenance in horse ?

A

20ml/kg/min induction

10ml/kg/min maintenance

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21
Q

T/F: for maintenance in horse, iso/sevoflurane is supplemented in intravenous drugs

A

True

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22
Q

What is the most common protocol for PIVA and TIVA?

A

A2 agonsit (xylazine, detomidine, romifidine, medetomidine)

Muscle relaxant (GGE or Midazolam)

Hypnotic agent (ketamine)

Provides.. narcosis, analgesia, and muscle relaxation

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23
Q

What are the goals of combining PIVA and inhalation anesthetic?

A

MAC reduction

Provide analgesia

Reduce adverse CVS effects

24
Q

What drugs are in PIVA for horse?

A

Ketamine
Medetomidine
Lidocaine

25
Q

What are advantages of TIVA over inhaltion all anesthetics?

A
Less CV depression 
Superior analgesia 
Less likely to move in response to surgical stimulus 
Decrease surgical stress
Lower morbidity and morality 
Better quality of recovery
26
Q

What are to two types of TIVA in horses ?

A

Triple drip -ketamine, Guaifenesin, xylazine/romifidine

Double drip

27
Q

Alternatively to a triple drip, you can top up you anesthesia with intermittent boluses. What can you use?

A

Ketamine

Diazepam/midazolam

28
Q

What lead configuration for ECG is used in horse

A

Lead 1 (base-apex)

29
Q

What reflexes can you use for monitoring anesthetic depth?

A
Palpebral reflex weak 
No nystagmus 
Weak anal tone 
Stable autonomic reflexes 
Non-responsive to surgical stimulus 

Too light: lacrimation, nystagmus, corneal reflex, tachypnea/tachycardia, movement

30
Q

What are signs that you anesthesia is too deep?

A

Absent palpebral reflex
Absent corneal reflex
Dry cornea
Bradypnea, apnea, bradycardia, and hypotension

31
Q

What are complications can occur in horse anesthesia ?

A
Sudden heart failure 
Hypotension 
Hypoventilation
Hypoxemia 
Myopathy
Myelopathy 
Excitement and ataxia 
Nasal obstruction 
Jugular vein thrombosis
32
Q

How can you treat anesthesia related hypotension ?

A

Address specific underlying problem
Reduce anesthesia admin
Volume resuscitation -crystalloid or colloids
Cardioacive drugs (dobutamine, phenylephrine)

33
Q

How can you manage hypoventilation during anesthesia ?

A

Mechanical ventilation
Set resp rate and volume

Target - 35-34mmHg pCO2

34
Q

What myopathies are associated with anesthesia?

A

With rhabdomyolysis

  • compartmental myopathy
  • malignant hyperthermia

Without rhabdomyolysis
-hyperkalemic periodic paresis

35
Q

What pathoglical changes occur in myopathy?

A

Myoglobinuria and hyperglobulinemia

Muscle enzymes (elevated CK, AST, and LDH)

Electrolyte

  • elevated P and K
  • decreased Na, Cl, and Ca

BUN and CREA elevated

Inflammatory leukogram

36
Q

What are predisposing factors to compartmental myopathy ?

A

Heavily muscled horse

Fit or nervous horse

Persistently low MAP <70mmHg

Improper positioning

Prolonged anesthesia time >2hours

Halothane

37
Q

What are signs of a compartmental myopathy?

A

6Ps (pain, paresis, paralysis, pallor, pulselessness, poikilothermia)

Failure to stand on specific muscle group

Muscle feels hard and is severely painful

Myoglobinuria-> renal failure

38
Q

How do you treat compartmental myopathy?

A

Fluids
Analgesic, muscle relaxant/ sedative

Oxygen radical scavengers: DMSO

Physiotherapy

Fasciotomy-decompression

39
Q

What are predisposing factors to malignant hyperthermia?

A

Mutations in ryanodine gene —> dysfunctional release of Ca

Halothane
Stress
Depolarizing muscle relaxants (succinylcholine)
Improper positioning

40
Q

Signs and symptoms of malignant hyperthermia

A
Profuse sweating 
Tachypnea 
Tachycardia and arrhythmia 
Hypertension 
Prolapse of third eyelid 
Flared nostrils 
Contracted masseters 
Muscle rigidity and twitching 
Myoglobinuria 
Death
41
Q

How can you prevent malignant hyperthermia?

A

Correct positioning and padding
Pre-anesthetic dantrolene
Maintain normal BP

42
Q

What is the treatment of malignant hyperthermia?

A
Dantrolene 
Water/alcohol bath 
ACP for vasodilation 
Na bicarb for acidosis 
TLC
43
Q

What is hyperkelemic period paralysis (HYPP)?

A

Generic in Quarter horses

Mutation resulting in failure of Na channels to deactivate - excessive Na influx and K outward flux

44
Q

What are signs of HYPP myopathy?

A
Respiratory distress and laryngeal paralysis 
Swaying 
Staggering 
Dog-sitting 
Recumbency 
Prolapse of eyelid
45
Q

How do you treat HYPP myopathy?

A

Acetazolamide
Dextrose
Ca gluconate
TLC

46
Q

What are possible causes of neuropathy ?

A

Ischemia, pressure, and stretching

47
Q

How can you prevent neuropathy?

A

Correct position and padding
Remove head halter during anesthesia
Maintain BP

48
Q

How can we see nasal edema as a complication in equine anesthesia?

A

Gravitational (hypostatic) fluid extravasation

—> keep nasal tube in place until horse stands and provide O2

49
Q

How can we reduce excitement during recovery?

A

Minimize stimulation

Sedate with romifidine/detomidine

50
Q

How should you premeditate a foal?

A

In presence of mother

Can used benzodiazepines in foals, doesn’t cause excitement like in adults

51
Q

What is used for induction of a foal?

A

Propofol, ketamine

52
Q

A one week old 45kg foal presents for anesthesia to surgically repair a patent urachus and an accompanying ruptured bladder.

For low long would you starve this foal before the anesthetic procedure ?

A

No fasting

Foals are not prone to regurgitation and are prone to hypoglycemia

53
Q

A one week old 45kg foal presents for anesthesia to surgically repair a patent urachus and an accompanying ruptured bladder.

What are 5 physiological complications that this foal is more predisposed to during anesthesia compared to normal adult horses?

A

Prone to hypoglycemia (high metabolic rate and low storage)
Low BP / High HR
Prone to hypothermia
Lower liver function -require less drugs
Respiratory system not fully developed- poor ventilation -> hypoxemia

54
Q

T/F: donkeys are more resistant to sedatives and anesthetics

A

True

-increase dose by 30%

55
Q

T/F: the half life of GGE is shorter in donkeys but they are more sensitive to ketamine

A

False

Ketamine half life is shorter —> expect more frequent top ups

More sensitive to GGE