TECHNIQUE

Catching and Handling of Stoats, Weasels etc. (Wildlife Casualty Management)
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Summary Information
Type of technique Health & Management / UK Wildlife Casualty Management / Techniques:
Synonyms and Keywords N.B. This information should be read in association with Wildlife Casualty Handling and Transport which contains background information together with links to the Electronic Library and Organisations (UK Contacts). The related Species pages contain similar linkages.
Description This page has been prepared for the "UK Wildlife: First Aid and Care" Wildpro module, and is designed for the needs of the following species: Martes martes - Pine marten, Mustela erminea - Stoat, Mustela nivalis - Weasel, Mustela putorius - Polecat, Mustela vison - American mink.

These species are within the family Mustelidae.

Handle with caution, wear stout leather gloves: these animals will bite and hold on and bites may be severe.

Catching and handling:

  • It may be possible to tempt animals of these species to enter a drainpipe leading into a box, as for ferrets; this would allow an individual to be caught and transported without any direct handling. (D25)
  • Handle with caution, wear stout leather gloves: these animals will bite and hold on and bites may be severe.
  • The animal may be gripped quickly with gloved hands around its neck and forequarters.(B199, D25)
  • The animal may be restrained with one hand holding the back of the neck and the other extending the hind legs and tail.(B16.7.w7)
  • Nets may be used for restraint of these species.(B123)

(B16.7.w7, B123, B199, D25)

  • A dog grasper may be used to handle Martes martes - Pine marten, Mustela putorius - Polecat, Mustela vison - American mink:
    • slide the dog grasper to just behind the forelegs of the animal;
    • once the grasper is in position, use it to quickly lift the animal and deposit it inside a suitable container.
    • (B151)

Restraint for examination and treatment:

  • Manual restraint of these extremely agile and fast-moving animals is difficult.
  • Examination and treatment are best performed under general anaesthesia.
  • Crush cages may be used for restraint of the larger species to allow intramuscular injection e.g. for induction of general anaesthesia.

General Anaesthesia and Sedation:

General Information:

  • Combination of intramuscular medetomidine and ketamine is commonly used for general anaesthesia in small and zoo animal practice in the UK; extrapolation of dose rates for companion animals from the manufacturers recommendations may be appropriate. Manufacturer's recommendations for feline general anaesthesia include "[Medetomidine] Domitor [Pfizer Limited] should be administered at a rate of 80mcg/kg [intramuscular] with a concomitant dose of 2.5 - 7.5mg/kg [intramuscular] of Vetalar [Pharmacia and Upjohn Ltd.] or Ketaset [Fort Dodge Animal Health](ketamine)." (B202) In extrapolating dose rates a number of issues must be remembered:
    • higher dose rates may be required for very nervous / excited / agressive animals who may initially over-ride the effects of anaesthesia
    • smaller animals with a higher metabolic rate may require proportionally higher dose rates; the reverse is also usually true for larger animals
    • collapsed, shock and/or dehydrate animals may required lower dose rates
      (V.w6, V.w26)
    • Sometimes there may be a requirement for additional "top-up" doses of injectable anaesthetics (V.w6, V.w26) and the following should be considered:
      • ideally, if a mask can be applied without excessive stress on the animal, masking it down with either isoflurane or halothane is usually the best option.
      • it is not desirable to reach the situation where additional doses are being given in order to reach initial stable anaesthesia whilst the first drugs are wearing off. It is all too easy to overdose in this situation. If three injections are not effective - if possible, it is highly advisable to stop the procedure, allow the anaesthesia to wear off and then repeat the procedure at a later date using higher doses initially.
      • when increasing dosages, careful consideration should be given both the side-effects of the drugs and the availability of reversal agents
      • If an intravenous injection can be given, it may allow more control over the depth of anaesthesia
      • if a top-up dose is required, the following rule of thumb is recommended:
  1. If there is little effect on the animal after 15 minutes (it is alert and reponsive), give a second full dose
  2. If the animal is clearly affected but still active after 15 minutes, give a 3/4 dose.
  3. If there is some degree of anaethesia, but a deeper level is required, give 1/2 dose.
  4. Beyond that - use best judgement.

(V.w6, V.w26)

 Suggested protocols for sedation and general anaesthesia include:

  • General anaesthesia may be induced using an induction chamber;
    • Isoflurane is a suitable anaesthetic agent and may be used for induction and for maintenance of general anaesthesia. (B205, D24, P20.1992.w1)
    • Halothane may also be used. (B205, P20.1992.w1)
    • A prolonged time to induction of general anaesthesia has sometimes been reported when using gaseous anaesthetic agents delivered by induction chamber for the induction of general anaesthetic in aquatic species which have the ability to breath-hold for extended periods.(P20.1992.w1)
  • General anaesthesia may also be induced using injectable anaesthetic agents such as ketamine; or ketamine combined with midazolam, diazepam, xylazine, medetomidine or acepromazine (P20.1992.w1).
  • Ketamine (5-10mg/kg) intramuscular is suggested for restraint of mink.(B123)
  • Ketamine 20-30mg/kg intramuscular is suggested for stoats and weasels.(B205)
  • Combination of ketamine with a sedative (e.g. benzodiazepine, alpha-2 agonist) is generally preferable to the use of ketamine alone. (V.w5, V.w6, V.w26)
  • The effects of medetomidine are normally reversed by injection of the agent atipamezole, unless otherwise indicated. (V.w5, V.w6, V.w26)
  • Ketamine 25mg/kg plus diazepam 25mg/kg intramuscular is suggested for stoats and weasels. (B205)
  • Alphaxalone/alphadalone (Saffan, Schering Plough Animal Health) 10-15mg (total steroid)/kg intramuscular is suggested for stoats and weasels.(B205)
  • Intubation of mustelids is relatively easy.(P20.1992.w1)
  • The length of starvation prior to induction of general anaesthesia should be appropriate for the species in question and the likelihood of regurgitation. Clinical judgement should be used as to the pros and cons of starvation in an emergency situation. Starvation may not be appropriate for small species with a high metabolic rate which must eat frequently to survive.
Appropriate Use (?)
  • Catch only if necessary.
  • Handling of wild animals should be minimised.
  • Consider design of accommodation and timing of treatments to minimise requirements for capture and handling.
  • Consider whether physical or chemical restraint is more appropriate.
Notes
  • Stoat and weasel: may be handled with stout gloves for protection.(B151)
  • Intubation of mustelids is relatively easy.(P20.1992.w1)
Complications/ Limitations / Risk
  • These animals are very agile, fast-moving and have sharp teeth: manual restraint is difficult.
  • Handle with caution: there is a considerable risk to handlers from bites (decreased risk from juveniles):
    • these animals will bite and hold on; bites may be severe.
  • A prolonged time to induction of general anaesthesia has sometimes been reported to occur when using gaseous anaesthetic agents delivered by induction chamber in aquatic species of mustelids with the ability to breath-hold for extended periods. (P20.1992.w1)
Equipment / Chemicals required and Suppliers
  • Dog grasper.
  • Stout leather gloves.
  • Strong nets.
  • Squeeze cage suitable for species of this size.
  • Appropriate drugs for chemical restraint/anaesthesia.
Expertise level / Ease of Use
  • Experience is advantageous for handling these animals safely. Inexperienced persons should seek appropriate advice and assistance from people with appropriate expertise.
Cost/ Availability
  • Appropriate nets, gauntlets, dog-catcher, squeeze cages may be available from specialist suppliers or veterinary suppliers.
  • Dog graspers may be available from e.g. specialist suppliers and veterinary suppliers.
  • Suitable gloves may be available from specialist suppliers, veterinary suppliers or some good pet stores.
  • These are variable costs associated with the purchase of equipment such as gloves and nets.
  • Nets may be hand-constructed from readily available materials.
  • Some drugs used for chemical restraint are expensive.
  • Drugs used for chemical restraint may only be available to veterinary surgeons or other licensed persons.
Legal and Ethical Considerations
Author Debra Bourne
Referee Becki Lawson and Suzanne Boardman
References

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