TECHNIQUE

Medetomidine - Ketamine Anaesthesia in Rabbits (Disease Investigation & Management - Treatment and Care)

Summary Information
Type of technique Health & Management / Disease Investigation & Management / Techniques:
Synonyms and Keywords --
Description An injectable anaesthetic combination suitable for sedation (lower dose) to surgical anaesthesia (higher dose).

Anaesthetic protocol

  • 1) Give medetomidine 0.15 - 0.25 mg/kg subcutaneously. (B601.16.w16)
    • This provides sedation. (B601.16.w16)
  • After five minutes, provide oxygen by face mask. (B601.16.w16)
  • Give metamine 10 - 15 mg/kg subcutaneously or intramuscularly. (B601.16.w16)
OR
  • 2) Mix medetomidine and ketamine in one syringe and give simultaneously, subcutaneously (preferred) or intramuscularly: 
    • Medetomidine 0.15 - 0.25 mg/kg plus ketamine 10 - 15 mg/kg (B601.16.w16)
    • Medetomidine 0.25 mg/kg plus ketamine 15 mg/kg. (J290.28.w2, J290.32.w4)
  • Loss of consciousness occurs after 5 - 10 minutes of both drugs being given subcutaneously, or within 2 - 5 minutes if they are given intramuscularly. (B601.16.w16)
  • Medetomidine 0.25 mg/kg plus ketamine 15 mg/kg provides about 15 - 30 minutes of surgical anaesthesia. (J290.28.w2)
  • Subcutaneous injection is better tolerated by the rabbit. (J290.32.w4)

Supplementation

  • For a longer duration of anaesthesia: 
    • Give butorphanol 0.1 mg/kg or buprenorphine 0.03 mg/kg; the triple combinations provide about 80 minutes of surgical anaesthesia. (B601.16.w16)
    • Or give medetomidine and ketamine, about one tenth of the original dose, diluted 1:10 in sterile water for injection and administered by slow intravenous injection, to effect. (B601.16.w16)
  • For deeper anaesthesia/additional analgesia:
    • A gaseous anaesthetic agent can be given e.g. isoflurane 0.5 - 1.0% (B601.16.w16) isoflurane 1.5 - 2.0%. (J290.32.w4); sevoflurane 1.0 - 1.5% (B601.16.w16)
    • Or additional medetomidine plus ketamine (approximately one third of the original dose; this is not recommended. (B601.16.w16)
  • Or use local anaesthesia at the surgical site. (B601.16.w16)

Anaesthetic reversal

  • Atipamezole, 0.5 - 1.0 mg/kg subcutaneously. This reverses the medetomidine. The duration of action of the ketamine is about 45 minutes; administration of atipamezole after 30-40 minutes produces rapid recovery. (B601.16.w16)
  • Note: atipamezole administration will reverse the analgesic as well as the sedative effects of medetomidine. An additional analgesic is required to maintain an appropriate level of pain relief. (B601.16.w16)
Appropriate Use (?)
  • For rabbits which are apparently healthy. (B601.16.w16)
  • The lower end of the dose rate provides anaesthesia adequate for endotracheal intubation (Endotracheal Intubation of Rabbits), but may not provide sufficient analgesia for major surgery. (B601.16.w16)
  • Medetomidine 0.2 mg/kg plus ketamine 10 mg/kg subcutaneously provides sufficient sedation for radiography. (B601.16.w16)
  • The higher end of the dose rate provides sufficient anaesthetic depth for e.g. ovariohysterectomy. (B601.16.w16)
  • Generally provides surgical anaesthesia for 30 - 60 minutes. (B601.16.w16)
Notes
  • Subcutaneous injection is tolerated better (gives less discomfort to the rabbit) than intramuscular injection, particularly with the higher volumes (i.e. at the higher dose rates). (B601.16.w16, J290.29.w2, J290.32.w4)
  • Subcutaneous injection produces a significantly slower onset of anaesthesia than intramuscular injection. (J290.32.w4, J290.32.w5)
  • This combination produces only moderate hypercapnoea. (B601.16.w16)
  • As an alternative, ketamine 35 mg/kg intramuscularly can be used with xylazine 5 mg/kg intramuscularly; this provides a slightly lower level of analgesia. (B601.16.w16)
Complications/ Limitations / Risk
  • Produces hypoxaemia which may be severe; oxygen supplementation should be given. (B601.16.w16, J290.28.w2, J290.29.w2)
    • Very low oxy-haemoglobin saturation levels measured in some rabbits was thought to be associated with peripheral vasoconstriction. (J290.32.w4)
  • Peripheral vasoconstriction occurs, therefore:
    • Placing an intravenous over-the-needle intravenous catheter may be more difficult. (B601.16.w16)
    • The mucous membranes are a pale, bluish colour even if the rabbit is being supplied with supplemental oxygen and is well oxygenated. (B601.16.w16)
    • If not supplied with supplemental oxygen the rabbit will appear severely hypoxic. (B601.16.w16)
    • Pulse oximetry may not be reliable. (J15.20.w2)
  • Usually hypotension. (J15.20.w2)
  • Not recommended for rabbits with a pre-existing fluid deficit, since this combination is known to produce moderate cardiovascular depression in other species. (B601.16.w16)
Equipment / Chemicals required and Suppliers
Expertise level / Ease of Use
  • This procedure should only be carried out by an individual with appropriate clinical training and practical experience.
Cost / Availability --
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 lagomorphs 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 any country, drugs are unlikely to be specifically licensed for use in non-domestic mammals. 
    • In Europe the prescription cascade must be followed, and the client's informed consent should be obtained, whenever a drug is used which is not licensed for use in a given species. (B284.5.w5)
    • 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).
Author Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referee Molly Varga BVetMed DZooMed MRCVS (V.w125)
References B601.16.w16, J15.20.w2 J290.28.w2, J290.29.w2, J290.32.w4, J290.32.w5

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