There are several highly infectious and potentially fatal diseases that can affect your rabbit. Fortunately vaccines have been produced that will protect your rabbit against two of these – myxomatosis and viral haemorrhagic disease (strains 1 and 2). To ensure that your rabbit is fully protected it is essential that it receives regular booster injections.
How do vaccines work?
Vaccines are given by injection under or into the skin in rabbits. They all work by training the white blood cells in your rabbit’s body how to recognise and attack the viruses or bacteria contained in the vaccine. This should prevent infection with that particular bug if your rabbit is in contact with it again.
Current vaccines fall into two main categories: ‘live vaccines’ which contain a strain of the bug which has been altered so that it cannot cause disease but does stimulate immunity, and ‘dead vaccines’ in which the bug has been killed by heat or chemicals. Each type has their pros and cons – live vaccines generally give better and longer-lasting protection but they can sometimes cause more side-effects. Live vaccines are not recommended for certain groups of rabbits, such as pregnant females. The combined Myxo-RHD vaccination which offers protection against Myxomatosis and VHD1 is a live vaccine. The VHD2 strain vaccines are all inactivated ‘dead vaccines’.
What is myxomatosis?
Myxomatosis is a disease caused by a virus. It only affects rabbits, but both wild rabbits and pet rabbits are susceptible. The virus causes severe swelling of the lips, eyelids and genitals. Wild rabbits suffering from this condition usually fall victim to predators, eg foxes, or are hit by cars. Pet rabbits can sometimes recover from the condition with very intensive nursing, but most are euthanased.
The virus causing myxomatosis is transmitted between infected and healthy rabbits by insects, particularly rabbit fleas, but also by flies. Cats often become infected by rabbit fleas and will bring these into your garden or inside your house. Therefore, even if your rabbit lives indoors or if you live in a city centre, far from places where wild rabbits live, your pet rabbit could still be at risk.
What is viral haemorrhagic disease?
Viral haemorrhagic disease (VHD or HVD) is a horrible viral condition that only affects rabbits. It is caused by a highly contagious virus which is transmitted from rabbit to rabbit, or on contaminated equipment, clothing and feed. Insects, rodents and birds may also be able to carry the virus and infect isolated rabbits (such as pet rabbits).
VHD1 is nearly always fatal; it causes massive bleeding (haemorrhage) from the internal organs and the animals die as a result of the overwhelming blood loss.
VHD2 is fatal in around 7-20% of cases, but as it kills slower it has more of a chance to spread. The virus often has very non-specific clinical signs which may just be that the rabbit seems slightly off-colour or may show no signs at all. There is no way of diagnosing or differentiating what strain of VHD a rabbit is affected with unless it is confirmed on post mortem.
When should my rabbit be vaccinated?
Rabbits can be vaccinated against myxomatosis and VHD1 from 5 weeks of age. The vaccination provides immunity for one year against both myxomatosis and VHD1. Myxomatosis is generally a seasonal disease, although it can occur all year round, and the numbers of cases peak significantly in the late summer/early autumn.
An annual combined booster provides adequate immunity for one year for both myxomatosis and VHD1. Vaccination for VHD2 depends on what vaccine your vet has access to. There is no UK based vaccine for VHD2 so a vaccine needs to be imported from Europe. Vets can now easily obtain vaccines for VHD2:
Filavac VHD K C + V: the most readily available vaccine; can be given from 10 weeks of age and an annual booster is sufficient except in high risk areas or high risk rabbits, eg show rabbits, rescue centres, etc, where a 6 monthly booster is recommended.
Cunivak RHD: can be given from 4 weeks of age and a second initial vaccination is needed 3 weeks after; an annual booster is sufficient thereafter. Not currently available in the UK.
Cunipravac RHD: available only in multidose vials that have to be used within 8 hours of opening. For this reason this vaccine is not normally used by vets for pet rabbits, although may be used for breeders who have multiple rabbits to vaccinate at the same time. The vaccine can be given from 4 weeks of age and requires a second initial vaccination 6 weeks after followed by 6 monthly boosters. The vaccine is oil based which can cause skin reactions.
With all VHD2 vaccinations, a 2 week gap between them and the Nobivac Myxo-RHD vaccine must be left since none of the vaccines have had trials to determine how they react with the Nobivac Myxo-RHD vaccine.
The combined Myxo-RHD vaccination is not recommended in pregnant does or bucks intended to be used for breeding, since safety in these groups has not been trialled sufficiently.
How is the vaccination given?
The vaccinations are given by injection usually into the scruff at the back of the neck. The old myxomatosis vaccination needed a small amount of the vaccine to be given intradermally (into the rabbit’s skin), but the combined Myxo-RHD vaccine and all the VHD2 vaccines do not require this and the entire volume is administered subcutaneously (under the skin) into the scruff of the neck.
Why is it necessary to have repeat vaccinations?
The protection given by most vaccines wears off in time. Booster injections ensure that your rabbit has continuing immunity against the diseases.
Do vaccines fail to work sometimes?
Occasionally a rabbit may not be fully protected against a condition, even after vaccination. This may be because the rabbit was already ill or was stressed when it was vaccinated and its immune system wasn’t working properly. Your vet will examine your rabbit before vaccination and if any signs of illness are detected will delay vaccination until your rabbit is well again.
Rabbits previously vaccinated with the Nobivac Myxo vaccine should respond to vaccination with the combined Myxo-RHD vaccination to ensure adequate protection against both diseases. Those rabbits vaccinated with other myxomatosis vaccines or those that have been exposed to the myxomatosis virus, may not develop a proper immune response to VHD1 following the combined vaccination. You should speak to your vet if you have any concerns.
There have been a small number of cases reported of rabbits vaccinated with the old myxomatosis vaccination contracting the disease. These rabbits exhibited symptoms of a very mild form of the disease and all recovered. In these cases, the vaccine may have protected them from the severe form of the disease. There have so far been no instances of this with the combined vaccine.
Can vaccinations be dangerous?
Sometimes your rabbit may seem ‘off colour’ for a day or two after its vaccination and the injection site may also become tender and swollen. If these effects do not wear off it is worth taking your rabbit back to see your vet. If you are concerned about any symptoms in your rabbit do not hesitate to contact your vet for reassurance or advice.