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General Anesthesia
in
Equine Emergencies
Page 1
Introduction
There are several emergent cases affect
horses like fractures , deep wounds ,
respiratory obstruction as well as surgical
intervention in case of dystocia.
There are several problems affect
administration of general anesthesia
in horses which lead to serious
physiological disturbances may lead
to death of the animal.
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Preanesthetic drugs
• Acepromazine 0.05 mg/kg IM
• Xylazine 2mg/kg IM
• Detomedine 20 µg/kg IM
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Induction of Anesthesia
• Kitamine + Xylazine + Guaifenesin
Xylazine 1.1 mg/kg IM then Guaifenesin 1.1
mg/kg IV after that Kitamine 1.3 mg/kg IV
give anesthesia for 25 min.
• Kitamine + Xylazine + Diazepam
Diazepam 0.2mg/kg IM and after 20 min
Xylazine 1.1 IV then Kitamine 2.2 mg/kg IV
give anesthesia for 40 min.
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Induction of Anesthesia
• Pentobarbitone Na 6.6 mg/kg 5%
• Guaifenesin 2.2 mg/kg 5%
• Pentobarbitone + Guaifenesin
2gm from pentobarbitone /1ltr of
Guaifenesin the dose is 2.2 mg/kg.
• Ketamine + Xylazine
Xylazine 1.1 mg/kg IV and then ketamine
2.2 mg/kg IV give anesthesia for 10 min.
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Maintenance of Anesthesia
1. IV injection
• Chloral hydrate 80 mg/kg IV.
• Equithesin (Chloral hydrate 28 gm +
Magnesium sulphate 14 gm +
pentobarbitone Na 6.5 gm ) give 80
mg/kg IV.
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Maintenance of Anesthesia
2.
•
•
•
Inhalation
Halothane 1.1 %.
Enfluthane 2.3%.
Isoflurane 1.5%.
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Contraindication
of
parentral general anesthesia
Cases of hepatitis and diseases of kidney.
Shock.
In very young animal (less than 1 month) and
also in the senile one.
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Side effects of parentral general
anesthetics
1. Barbiturate:
Thiopentone sodium:
• Induction apnea due to central inhibition
of respiratory center.
• Arrhythmia: due to direct affection on
myocardium .
• Oligurea: liberation of ADH due to
stimulation of supraopticohypophyseal
system.
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Pentobarbitone sodium:
• Prolonged recovery period if used alone.
• Hypotension due to dilation of peripheral
blood vessels.
• Tachycardia due to central inhibition of
vagus nerve.
• Respiratory failure due to inhibition of
respiratory centre in the medulla
oblongata.
• fetus mortality due to crossing the BPB.
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Narcotics
Chloral hydrate:
• Prolonged recovery period (1-4 hrs).
• Hypotension due to inhibition of vasomotor
center in the medulla oblongata.
• Bradycardia due to vagal activity.
• fetus mortality due to crossing the BPB.
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Steroidal anesthetic agent
Kitamine:
• Not good for horses due to convulsions
more than inhibitions.
• Transient apnea.
• Aspirated pneumonia due to affection of
swallowing reflexes.
• Hypertension and tachycardia.
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Side effects of inhalant general
anesthetics
Diethyl ether
•
•
•
Production of saliva and mucous.
Coughing and apnea.
Acidosis due to decrease the pH and
serum bicarbonate.
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Halothane
• Hypoxia due to inhibition of ventilation and
increase shallow respiration.
• Dilation of trachea due to direct affection
on the smooth muscles so it is used in
patient with asthma (advantage).
• Dilation of blood vessels of skeletal
muscles so can’t be used in case of
severe hemorrhage.
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Problems facing general anesthesia
cardiovascular system
Bradycardia:
•
•
Atropine sulphate + fluid therapy.
Stop or decrease administration of drugs
and give positive ventilation.
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Tachycardia
• Stop administration of drugs.
• Positive ventilation and fluid therapy
(increase Co2 lead to increase of heart
beats.
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Respiratory system
– Decrease respiratory rate or apnea:
•
•
Decrease the anesthetic depth.
Improve ventilation.
– Increase respiratory rate:
•
•
Increase anesthetic depth.
Increase Co2 in blood lead to increase
respiratory rate
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General anesthesia in equine
emergencies
These points should be regarded:
• Correction the status of the animal before
anesthesia by administration fluids,
NaHCo3, antibiotics.
• Placing the nasogastric tube.
• Activation of ventilation.
• Give supportive drugs as calcium
solutions.
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Wounds
• Suturing of wound.
• Using xylazine alone or with morphine,
phenothiazine tranquilizers are contraindicated
due to hypotensive effect.
• If these tranquilizers are used then must give
norepinephrine with fluids.
• In anesthesia can use Guaifenesin with
ketamine.
• Nitrous oxide is contraindicated due to decrease
the cardiac output.
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Fractures
• Anesthesia by mephenesin derivatives as
Guaifenesin cause muscles relaxation with
less affect on the cardiovascular and
respiratory systems.
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Dystocia
• Anesthesia by mephenesin derivatives as
Guaifenesin if the epidural anesthesia was
not enough.
• Guaifenesin can cross BPB but with no
noticeable inhibition to the vital organs of
fetus.
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CS. Operation
• Guaifenesin can be used with positive
ventilation.
• After getting the colt out from uterus
thiobarbiturate can be added to the anesthetic
regimen or administration of halothane by
endotracheal tube.
• Halothane and enfluthane decrease the uterine
contractility and decrease the bleeding.
• Nitrous oxide can be used safely after getting
colt from uterus, opioids can be given as well as
benzodiazepine compounds.
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Colic
• Pethidine IM with high doses because the low
doses can’t give the required effect.
• Xylazine and Detomedine with low doses can
give a good effect besides there are no negative
effects to the digestive canal.
• Disappearing the signs of pain in not treated
patient is bad prognosis which usually related to
the explosion the dilated organ.
• Acepromazine cause hypotension with limited
importance in the treatment of pain of colic.
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