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.

Precautions 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 renal failure.

Updated October 2013