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Alfaxan® in Pet Rabbits
Alfaxan® is now licensed for induction of anaesthesia in pet rabbits.

Rabbits are the 3rd most commonly anaesthetised pet in the United Kingdom70 and to achieve best practice outcomes it is vital to understand the unique physiology, behaviour and anaesthetic requirements of rabbits.

The CEPSAF study70 showed that rabbits had 7 times greater overall greater risk of anaesthetic death than dogs, so it is clear there must be some differences that need consideration before anaesthetising rabbits.

The CEPSAF study70 showed that rabbits had 7 times greater overall greater risk of anaesthetic death than dogs, so it is clear there must be some differences that need consideration before anaesthetising rabbits.

Behaviour

Rabbits are prey animals so if confronted with the scent, sight or sound of a predator, such as dogs and cats, stress responses will be initiated – even if the rabbit is well handled and healthy. Stress results in changes in physiology through increased circulating cortisol and catecholamines, which is not ideal when anaesthetising any patient.

Physiology

The uniqueness of rabbit physiology means they need to be managed differently to dogs and cats. For example, rabbits should not be fasted prior to anaesthesia, as this will put them at risk of hypoglycaemia and gastrointestinal stasis. Other physiologic differences exhibited by rabbits that should be considered are outlined in Table A.

Table A: Some key physiological differences between rabbits and other species
Consideration Impact on anaesthetic procedures
Prey species More likely to exhibit a stress response with high ciruclating cortisol and catecholamins
Hind gut digester Requires continual movement of food through gut to maintain normo-glycaemia and intestinal motility
Circulating Atropinase Rapid breakdown and therefore lack of effect from atropine administration

Anatomy

There are multiple anatomical differences that need to be considered when anaesthetising rabbits. One obvious difference is that they are obligate nose breathers, and as a result can be more difficult to intubate than the average dog or cat. Other anatomical differences that can impact on anaesthetic risk are outlined in Table B.

Table B: Some key anatomical differences between rabbits and other species
Consideration Impact on anaesthetic procedures
Obligate nose breather Can be slightly more challenging to intubate and upper respiratory disease can cause serious health issues
Small lung capacity Caution is required when mechanically ventilating and any excessive deadspace can compromise the patient
Continual teeth growth Moderate oral cavity disease can lead to serious health issues and make intubation more difficult
Intestinal fill effect Impedance to normal ventilation from gut fill means rabbits often benefit from slightly raised head position, especially when in dorsal recumbency
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Pre-Anaesthetic checks

  • Ensure the rabbit has food and water until being placed in their carrier and preferably whilst in the carrier as well
  • If they have a bonded companion, recommend they are presented together to the clinic
  • The owner has brought enough food from home to feed the rabbit/s during the stay

At admission, rabbits should avoid waiting in reception areas with dogs and cats.

A minimal time between admission and anaesthesia is preferred for rabbits (the longer a rabbit is in a strange environment surrounded by the scent, sight and sounds of predators the more stressed it will become).

Recommended evaluations that should occur pre-anaesthesia.


Parameter Assessment
Body Condition Score Ensure that patients are weighed and an appropriate condition score is applied. Overweight rabbits may benefit from delaying elective procedures to allow weight loss
Cardiovascular System Pink Mucous Membranes with good refill
Heart rate (135 to 325 bpm)
Regular rhythm
Respiratory Rate Regular rythm, not laboured, clear on auscultation
Respiratory Rate (40 to 60 bpm]
Body Temperature38.5 - 40℃
Basic Laboratory Parameters PCV - 33 to 45%
TP - 5.4 to 7.3 g/dL
Blood Glucose - 80 to 150 mg/dL

Alfaxan® and Anaesthetic Induction of Rabbits

Numerous published peer-reviewed papers have investigated Alfaxan as an anaesthetic induction agent for rabbits. 12–14 Controlled intravenous administration of Alfaxan offers a wide safety margin and an excellent cardio-respiratory profile, making it an excellent choice for anaesthetic induction of rabbits. Alfaxan produces

  • good muscle relaxation,
  • smooth transition from conscious to anaesthetised,
  • good conditions for endotracheal intubation,
  • the ability to titrate the dose to required anaesthetic depth,
  • the ability to top-up if required and
  • rapid clearance and recovery.

When first learning to use Alfaxan in rabbits, draw up the full labelled dose of Alfaxan (4 mg/kg for premedicated rabbits) and administer it intravenously, slowly until the patient is fully anaesthetised and can be intubated.

Controlling the rate of administration can be best achieved by placing an intravenous catheter in a marginal ear, cephalic or saphenous vein and aiming to administer ¼ of the drawn-up volume every 15 seconds. Please note: small vessels like marginal ear veins may spasm if cold fluid is administered into them (see Diagram A), refer to the SPC for more information.

Alfaxan Rabbit Diagram 1

Diagram A showing the location of the main ear veins in the rabbit and catheter placement.

Intubation

Rabbits are obligate nose breathers. As a result, any food in the mouth can be gently flushed out with water prior to attempting intubation, with little risk of aspiration.

Positioning a rabbit to allow dislocation of the soft palate and allow visualisation of the larynx is shown in Diagram B

Use of local anaesthetic administration to the larynx may allow for easier intubation and decreased risk of laryngospasm, however it is important to remember that local anaesthetic does not take effect instantaneously. Visualising the larynx when placing an endotracheal tube can be aided by use of a laryngoscope, otoscope or endoscope.

An alternative to intubation is the use of a laryngeal mask device. Correct placement of these devices requires some training. It is highly recommended when securing airways that you confirm placement using an End-Tidal CO2 monitor.

Alfaxan Rabbit Diagram 2

Diagram B: Showing optimal positioning of the rabbit to allow dislocation of the soft palate and visualisation of the larynx.

Maintenance

Anaesthesia can be maintained with isoflurane or sevoflurane. 

It is important to consider:

  • The small respiratory tidal volume necessitates minimal dead space
  • Minimal excursions will be seen in the rebreathing bag
  • Heart rate changes little in response to changes in anaesthetic depth so breathing rate and pattern are more useful indicators of this

Gastrointestinal fill can add pressure to the diaphragm and interfere with ventilation, so slight elevation of the thorax is recommended.

Recovery

The recovery area should be warm, well separated from dogs and cats and have the crash and re-intubation equipment on hand.

Alfaxan is rapidly cleared by rabbits, however the effects of other drugs like medetomidine may still have significant effects in the recovery period. Judicious use of reversal agents such as atipamezole can be considered. Extubation of the patient can be performed when they exhibit increased jaw tone and tongue movements. Pain relief is recommended where appropriate.

Early re-introduction to a companion and early re-introduction of fluids and feeding are considered very important for minimising stress and maintaining healthy gastrointestinal function.

Resources

Rabbit Bpa

Best Practice Anaesthesia In Pet Rabbits

Best Practice Anaesthesia In Pet Rabbits

Alfaxan Dose Chart

Alfaxan® Dose Chart

Guidelines as to the recommended dose of Alfaxan® in cats, dogs and pet rabbits.

Faqs

Alfaxan Frequently Asked Questions Chart

The answers to the most common questions we are asked about Alfaxan in dogs, cats and pet rabbits

Alfaxan Ukrecording

Getting the most out of Alfaxan

A 35 minute presentation covering what Alfaxan is and how to use it to achieve the best anaesthetic experience for you patient.

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Rabbits are different

A 13 minute presentation on how rabbits differ in relation to anaesthesia compared to cats and dogs.

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Considerations for Supporting Anaesthetised Patients

Maintaining anaesthesia in the rabbit is not as straightforward as often thought. This short presentation goes through the best way to support rabbits during maintenance.

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Considerations when Recovering and Discharging Rabbits

Recovery is considered to be one of the most critical stages of anaesthesia -particularly in the rabbit. Find out why and what to do in this short presentation.

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Considerations when booking in and admitting rabbits

An 11 minute presentation highlighting that ensuring an optimal outcome for your rabbit patients starts at the time of making the appointment.

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Pre-Anaesthetic Planning and Induction

A short presentation outlining how important pre-anaesthetic planning is in rabbits and best practice induction.

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The low impact of Alfaxan on cardiorespiratory parameters in dogs and cats have been appreciated by vets for years and now these benefits are now also available to pet rabbits.

The low impact of Alfaxan on cardiorespiratory parameters in dogs and cats have been appreciated by vets for years and now these benefits are now also available to pet rabbits.

Repeatable. Reliable. Relax.