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Provet for educational purposes only.
You should seek the advice of your
veterinarian if your pet is ill as only he or she can correctly advise on the
diagnosis and recommend the treatment that is most appropriate for your pet.
Halothane is is
still used but not a commonly as isofluorane. It is a safe induction and maintenance anaesthetic, indeed there are no definite
contraindications to it's use according to it's legal datasheets (Merial
Animal Health, 2013). However, there are precautions which should be taken.
to take when administering halothane include :
- Halothane potentiates the effects of non-depolarising muscle
relaxants (eg gallamine, d-tubocurarine) so the dose rate of these drugs
should be reduced if they are to be used concurrently
- If alpha-2-adrenreceptor agonists have been used as pre-medication care
is required when administering halothane because it sensitises the
myocardium (eg to catecholamines including adrenaline), indeed some
authors call the concurrent use of adrenaline a contra-indication to the
use of halothane (The Veterinary Formulary 4th Edition - RPS). This
also means that animals should not be allowed to get frightened, stressed
or excited prior to the use of halothane.
- Cardiovascular and respiratory depression occur as a dose-related
response with halothane and both cardiac and respiratory function should
be monitored during the anaesthetic period. Excessive depression should be
avoided by decreasing the dose rate of halothane and cardiopulmonary
resuscitation should be performed if respiratory or cardiac arrest occurs.
- Malignant hyperthermia is rare but it has been reported to occur in
pigs, horses and dogs during halothane anaesthesia
- Halothane delays uterine involution following Caesarian section and
ecbolic drugs have been recommended.
- Halothane can cause hepatic damage following repeated exposures. Great
care should be taken if using halothane in patients with pre-existing
impairment of liver function.
- The dose of halothane delivered by vapourisers can only be considered
reliable of the vaporiser has been regularly serviced because halothane
contains thymol as a preservative and this substance causes vaporiser
controls to stick and causes occlusion of ports, altering gas flow rates.
- Adverse effects of halothane (other than those mentioned above) include
vasodilation, hypotension and shivering and tremors during the recovery
phase. So, care should be taken when using halothane in animals that have
pre-existing renal disease and renal blood flow should be maintained by
setting up an intravenous fluid line in patients at risk to develop acute
Updated October 2013