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
What are advantages of TIVA over inhaltion all anesthetics?
``` 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
What are to two types of TIVA in horses ?
Triple drip -ketamine, Guaifenesin, xylazine/romifidine Double drip
27
Alternatively to a triple drip, you can top up you anesthesia with intermittent boluses. What can you use?
Ketamine Diazepam/midazolam
28
What lead configuration for ECG is used in horse
Lead 1 (base-apex)
29
What reflexes can you use for monitoring anesthetic depth?
``` 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
What are signs that you anesthesia is too deep?
Absent palpebral reflex Absent corneal reflex Dry cornea Bradypnea, apnea, bradycardia, and hypotension
31
What are complications can occur in horse anesthesia ?
``` Sudden heart failure Hypotension Hypoventilation Hypoxemia Myopathy Myelopathy Excitement and ataxia Nasal obstruction Jugular vein thrombosis ```
32
How can you treat anesthesia related hypotension ?
Address specific underlying problem Reduce anesthesia admin Volume resuscitation -crystalloid or colloids Cardioacive drugs (dobutamine, phenylephrine)
33
How can you manage hypoventilation during anesthesia ?
Mechanical ventilation Set resp rate and volume Target - 35-34mmHg pCO2
34
What myopathies are associated with anesthesia?
With rhabdomyolysis - compartmental myopathy - malignant hyperthermia Without rhabdomyolysis -hyperkalemic periodic paresis
35
What pathoglical changes occur in myopathy?
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
What are predisposing factors to compartmental myopathy ?
Heavily muscled horse Fit or nervous horse Persistently low MAP <70mmHg Improper positioning Prolonged anesthesia time >2hours Halothane
37
What are signs of a compartmental myopathy?
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
How do you treat compartmental myopathy?
Fluids Analgesic, muscle relaxant/ sedative Oxygen radical scavengers: DMSO Physiotherapy Fasciotomy-decompression
39
What are predisposing factors to malignant hyperthermia?
Mutations in ryanodine gene —> dysfunctional release of Ca Halothane Stress Depolarizing muscle relaxants (succinylcholine) Improper positioning
40
Signs and symptoms of malignant hyperthermia
``` Profuse sweating Tachypnea Tachycardia and arrhythmia Hypertension Prolapse of third eyelid Flared nostrils Contracted masseters Muscle rigidity and twitching Myoglobinuria Death ```
41
How can you prevent malignant hyperthermia?
Correct positioning and padding Pre-anesthetic dantrolene Maintain normal BP
42
What is the treatment of malignant hyperthermia?
``` Dantrolene Water/alcohol bath ACP for vasodilation Na bicarb for acidosis TLC ```
43
What is hyperkelemic period paralysis (HYPP)?
Generic in Quarter horses Mutation resulting in failure of Na channels to deactivate - excessive Na influx and K outward flux
44
What are signs of HYPP myopathy?
``` Respiratory distress and laryngeal paralysis Swaying Staggering Dog-sitting Recumbency Prolapse of eyelid ```
45
How do you treat HYPP myopathy?
Acetazolamide Dextrose Ca gluconate TLC
46
What are possible causes of neuropathy ?
Ischemia, pressure, and stretching
47
How can you prevent neuropathy?
Correct position and padding Remove head halter during anesthesia Maintain BP
48
How can we see nasal edema as a complication in equine anesthesia?
Gravitational (hypostatic) fluid extravasation —> keep nasal tube in place until horse stands and provide O2
49
How can we reduce excitement during recovery?
Minimize stimulation Sedate with romifidine/detomidine
50
How should you premeditate a foal?
In presence of mother Can used benzodiazepines in foals, doesn’t cause excitement like in adults
51
What is used for induction of a foal?
Propofol, ketamine
52
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 ?
No fasting Foals are not prone to regurgitation and are prone to hypoglycemia
53
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?
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
T/F: donkeys are more resistant to sedatives and anesthetics
True -increase dose by 30%
55
T/F: the half life of GGE is shorter in donkeys but they are more sensitive to ketamine
False Ketamine half life is shorter —> expect more frequent top ups More sensitive to GGE