When something goes wrong with an animal’s nervous system, it’s very upsetting, and it’s easy to panic. People often make generalisations, and leap to the wrong conclusion. He’s falling over! He’s had a stroke! He’s dragging his back legs! To help animals, it’s important for vets to be as objective as possible, making a careful note of precisely which part of the nervous system has gone wrong. Vets do this using a specific examination procedure, known as the “neurological examination”. There are tick sheets available to make it easier for vets: various aspects of the nervous system are examined individually, and at the end, it’s then easier to be specific about the precise diagnosis. Only then can the correct treatment and prognosis be given.
At last week’s London Vet Show, there was a fascinating lecture, sponsored by Supreme Pet Foods, which dealt with the subject of neurological examinations in rabbits. As many rabbit owners will know, diseases of the nervous system are common. However rabbits are very different creatures to dogs and cats: they are prey animals rather than predators, and as a consequence, their nervous system doesn’t always behave in the same way. Rabbits are especially sensitive to stress, and they tend to mask their fear by staying still. Anyone who has examined rabbits will know this: they tend to stay very passive until the fear is too much, and then they panic explosively, trying to jump out of your arms. This type of temperament means that rabbits react differently when their nervous system is examined. The lecturer carried out a field study, during which she made a careful comparison of a standard neurological examination in rabbits compared to other pets, and she came up with some useful tips.
First, she listed the four main types of disease of the nervous system seen in rabbits: head tilt, weakness or paralysis of the back legs (or all four legs), seizures (fitting) and “miscellaneous” (muscle weakness, strange gaits, blindness and other oddities). There’s a long list of possible causes of these problems, from brain diseases (including a common fungal parasite called Encephalitozoon cuniculi), to viral and bacterial infections, to spinal problems (including broken backs and slipped discs), to heat stroke, metabolic disorders and many others. In all cases, whatever the cause, the neurological examination is a key to whittling down the list of possibilities.
So how are rabbits different to dogs and cats?
First and most importantly, rabbits don’t show a pain response in the same way. With dogs and cats, it’s easy to tell if they can feel their toes by squeezing them: if sensation is normal, they pull their foot away from you. Rabbits often don’t do this: they stay utterly still, however hard you squeeze their toes. It doesn’t mean they aren’t feeling it: they just don’t react because in the wild, it makes more sense to “play dead” in the hope that the creature that’s hurting you will just go away.
Secondly, some of their reflexes are exaggerated. If you tap a dog’s knee with a rubber hammer, there’s a similar type of small “kick” reflex to a human. In rabbits, the same test elicits a sharp, exaggerated kick, perhaps reflecting the wound up stressed nervous system of the rabbit. If a dog had a reflex kick like this, you’d think there was something strange wrong with them: it’s normal in a rabbit.
Third, some of their reflexes are diminished or absent: for example, rabbits don’t have a “menace” reflex (if you wave your hand towards a dog’s eye as if you are about to hit them, they blink automatically, like humans: this is the menace reflex. Rabbits don’t do this). Other reflexes in rabbits’ eyes are also different: their pupils don’t always narrow and widen in the same way as other creatures.
There are two sets of take home messages here.
First, if you’re a vet, remember to expect different results from other pets when you’re assessing rabbits with neurological problems.
And second, if you’re a rabbit owner, remember to take your pet to a vet with an interest in rabbits: all vets are trained in the essentials of rabbit medicine, but when it comes to complex disease, the more rabbits that a vet sees, the better they will be at rabbit-specific subtleties like neurological examinations.