It is important to have your pet rabbit neutered for health and welfare reasons. However, rabbits need to be anaesthetised for this, and it is a common belief that they are more prone to dying during or directly after anaesthesia when compared to, say, cats or dogs. This article explains whether this reputation is deserved, and how recent advances have made anaesthetics much safer for bunnies. 

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Why is it a good idea to get my rabbit neutered? 

Many of the reasons for having your rabbit neutered are the same as those for cats and dogs. There is the obvious one, namely, to stop unwanted breeding. As everybody knows rabbits, well, they breed like rabbits.

Better behaved bunnies

Also, as with dogs and cats, neutering can reduce unpleasant and unwanted behaviours. This includes urine spraying, mounting and aggression to other rabbits. Female rabbits are as likely to display these behaviours as males. 

Happy bunnies

But won’t keeping my rabbit on its own sort out both problems? This is a question I often hear asked. 

Not necessarily. 

Rabbits are super social creatures. Keeping them on their own is seriously bad for their well-being. Imagine living with COVID confinement rules forever. Equally, housing unneutered male-male or female-female pairs is also not recommended. This can result in vicious fighting and bullying. The happiest pet bunnies are neutered and harmoniously bonded with rabbity chums. 

Reduce the risk of cancer

A further benefit of neutering is preventing malignant uterine (womb) tumours in female rabbits. This is an extremely common cancer that affects at least 15% (that’s 3 in 20) of unneutered female rabbits and is a common cause of early death. 

The neutering of rabbits is essentially the same as cats and dogs (removal of the testicles for males, removal of the ovary and uterus for females). Apart from the usual potential complications like wound infection, there are no long-term downsides to neutering your rabbit. But what is it with rabbits and anaesthetics? To properly understand this, we will need to crunch some numbers and get to grips with rabbit physiology. 

So are anaesthetics more risky for rabbits?

The most comprehensive data available looking at rabbit anaesthetic risk comes from a study that recorded what happened during and after anaesthetics of 7,652 healthy rabbits in veterinary practices between 2002 and 20041. They found that rabbits were about 14 times as likely to die within 48 hours of having an anaesthetic than dogs and 6 times as likely as cats. 

Although the actual numbers were small, this study confirmed there was something about rabbits that made them more sensitive to anaesthetics. 

The big problem with this data is that it is almost 20 years old, and it has not yet been updated. Vets’ understanding and management of rabbit anaesthesia in that time has vastly improved and this should mean that the actual risk for rabbits these days is very much lower. 

Why are Rabbits so sensitive to anaesthetics? 

In truth, we don’t really know, although there are many theories. Rabbits are prey animals and, to help them escape predators, have a highly developed acute stress response (better known as “fight or flight”). This results in higher levels of stress hormones, such as cortisol and adrenaline. This can make the heart more sensitive to anaesthetic drugs. 

Rabbits also have a specialised digestive system called hind-gut fermentation. This means they are prone to something called gut-stasis, where the intestines effectively stop moving. Gut-stasis is rapidly fatal if left untreated. It is not a disease, but usually a reaction to something underlying.

There is a wide range of triggers, including stress, pain and some drugs… which are all potentially features of neutering. Clinical signs include a reduction in food intake, listlessness and reduced faecal pellet production. Vets will ensure rabbits are monitored very closely for signs of gut-stasis for at least 48 hours after an anaesthetic. 

How has rabbit anaesthesia improved? 

I have seen rabbit anaesthesia in practice evolve beyond all recognition in the last 20 years. Measures can be put in place to reduce anaesthetic risk from the moment your rabbit enters the clinic. This includes having rabbit-only wards, where they are kept away from the sight, sound or smell of cats and dogs. There is also an entire range of newer, safer anaesthetic drugs. Your vet will make sure your pet has highly effective pain relief and anti–gut-stasis medication, which you can continue to give at home.

The cornerstones of anaesthetic safety, for any species, are intubation of the airways and placement of an intravenous catheter. An airway tube means that your vet can ensure your rabbit is getting enough oxygen and control the level of anaesthesia more precisely. Whereas an intravenous catheter enables your vet to administer anaesthetic medications at more accurate doses and, they can rapidly provide support for the circulation if blood pressure falls too low, a common side-effect of anaesthetic medication. 

In the past, anaesthesia on rabbits without intubation or intravenous catheterisation was the norm, mainly because they have very awkward anatomy. Rabbits have a tiny gape with their little mouths. You can see this for yourself if you type “rabbit yawning” on google. They also have an elongated oral cavity. Together, these features make intubation very difficult. Happily, new techniques have been developed with modern anaesthesia, which makes intubation and airway control easier. Also, advances in catheter technology mean that there are now catheters tiny enough to use in rabbit ear veins, which can be placed painlessly and are well tolerated. 

Rabbit anaesthetics have quite literally come on leaps and bounds in two decades. The risk cannot be eliminated altogether, but it is small when measured up against the lifelong health and welfare benefits your rabbit can enjoy by being neutered. 

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References

1. Brodbelt DC, Blissitt KJ, Hammond RA, et al. The risk of death: The confidential enquiry into perioperative small animal fatalities. Vet Anaesth Analg. 2008;35(5):365-373. doi:10.1111/j.1467-2995.2008.00397.x