TECHNIQUE

Halothane Anaesthesia in Waterfowl (Disease Investigation & Control - Treatment and Care)

Summary Information
Type of technique Health & Management / Disease Investigation & Control / Treatment & Care / Techniques:
Synonyms and Keywords See also:
Description N.B. Information given in this page is to be used in conjunction with the relevant sections on Anaesthesia and Chemical Restraint within "Treatment and/or Control".

Before using any anaesthetic agent or combination of agents the manufacturer's data sheet on the agent or agents concerned should be consulted, taking particular note of any contra-indications and operator warnings.

  • Induction concentration of 3% suggested (B11.9.w20).
  • Or starting concentration of 0.5-1% gradually increased to 2.5-3.0%, giving slower induction but less risk (B14, P7.1.w4).
  • Induction may occur in two to five minutes at level of 2-3% (B13.39.w16); 7.1 +/1 2.0 minutes were required at 3.5% to anaesthetise adult Pekin ducks Anas platyrhynchos domesticus (J13.51.w1).
  • Maintenance concentration of 1.0-2.0% (P7.1.w4) or 2.0-2.5% (B14) suggested.
  • Recovery may vary, but is usually 5-20 minutes (B13.39.w16).
Appropriate Use (?)
  • May be used for induction.
  • May be used for maintenance.
  • Use with oxygen.
  • Easy induction, smooth recovery.
  • Relatively low solubility allows relatively rapid induction/change in anaesthetic level.
Notes
  • Therapeutic ratio (safety margin) 3.0.
  • N.B. Avian anatomy, with "bellows" system of air sacs may lead to a period of increasing depth of anaesthesia after induction with high concentration, despite reduction in the concentration of anaesthetic gas being delivered by the vaporiser (B11.9.w20).
  • Solubility relatively low (blood/gas coefficient 2.3), but higher than isoflurane - potential for redistribution back into the blood from other body compartments.
  • 15-20% metabolised. Metabolism and recovery impaired with significant liver disease.
  • Induction time 7.1 +/- 2.0 minutes in trial in Pekin ducks (Anas platyrhynchos domesticus) at an induction concentration of 3.5%, oxygen flow rate of 3.0litres/minute (J13.51.w1).
  • Non-flammable under normal conditions.
Complications/ Limitations / Risk
  • Slower recovery than isoflurane (due to distribution and metabolism).
  • Poor muscle relaxation.
  • Poor analgesia.
  • Marked depressive effect on respiration (4.5 +/- 1 breath/minute, compared to baseline 19+/- 4 breaths per minute) (J13.51.w1).
  • Significantly increases heart rate (J13.51.w1).
  • Significantly decreases blood pressure (J13.51.w1).
  • Moderate depressive effect on myocardium.
  • Sensitises myocardium to catecholamines - may result in arrhythmias: contraindicated if bird excited at the time of induction.
  • Metabolism and recovery impaired with significant liver disease.
  • Contraindicated in individuals with hepatic dysfunction or cardiovascular disease.
  • Ventilation may be required to counteract respiratory depression.
  • Overdose may cause apnoea and cardiac arrest simultaneously.
  • May cause liver disease in chronically exposed personnel.
Equipment / Chemicals required and Suppliers Requires calibrated vaporiser.

Halothane: e.g. Halothane-RM (Merial Animal Health Ltd.), a clear, colourless volatile liquid; Fluothane (Schering-Plough Animal Health), a colourless volatile liquid, chemically 2-bromo-2-chloro-1,1,1-trifluoroethane, stabilised with thymol 0.01% (Halothane Ph. Eur) (B90).

Expertise level / Ease of Use Procedure should only be undertaken by an individual with appropriate clinical training and practical experience; this would usually be a veterinarian or someone with advanced veterinary technician training.

N.B. Whenever an anaesthetic is undertaken, the anaesthetist must be familiar with emergency protocols. Consideration must be given as to the availability of equipment required to monitor the anaesthetic plane of the animal being anaesthetized and any equipment/drugs required for revival. It is advisable to calculate the doses of any revival agents which may be required in an emergency BEFORE COMMENCING the anaesthetic (V.w6).

Cost/ Availability Relatively inexpensive.
Legal and Ethical Considerations In some countries there may be legislation restricting the use of this type of technique to licensed veterinarians. For example in the UK: "The Veterinary Surgeons Act 1966 (Section 19) provides, subject to a number of exceptions, that only registered members of the Royal College of Veterinary Surgeons may practice veterinary surgery."(see: LCofC1 - RCVS Guide to Professional Conduct 2000 - Treatment of Animals by Non-Veterinary Surgeons).).

Use of Drugs (Medication):

  • Many drugs are not registered for use in particular bird species and care should be taken in their use, with proper regard for possible toxic effects. Consideration should be give to relevant legislation regarding the use of drugs.
  • In the UK, guidelines regarding the use of drugs are set out in the Royal College of Veterinary Surgeons Guide to Professional Conduct 2000: (see: LCofC1 - RCVS Guide to Professional Conduct 2000 - Choice of Medicinal Products).

Before using any anaesthetic agent or combination of agents the manufacturer's data sheet on the agent or agents concerned should be consulted, taking particular note of any contra-indications and operator warnings.

Author Debra Bourne
Referee  
References J13.51.w1, B10.7.w17, B11.9.w20, B13.39.w16, P7.1.w4, B90, V.w6

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