New risk to rabbit health
In the UK we vaccinate our pet rabbits against two diseases – both of which can be deadly. These diseases are Rabbit haemorrhagic disease and Myxomatosis. They are both prevalent in the UK meaning that all rabbits are at risk of becoming infected. Rabbit haemorrhagic disease has developed a new strain that has been identified in the UK – here is what you need to know as a rabbit owner…
Rabbit haemorrhagic disease (RHDV) is a highly lethal disease in rabbits that is caused by a calicivirus. Classical RHDV is widespread throughout the world and can prove fatal. Once a rabbit is infected with RHDV it can take 1-4 days before clinical signs are seen. The virus replicates in many tissues within the body including the lungs, liver and spleen. Infection causes damage to these organs and affects blood clotting, blood clots within vessels and causes haemorrhages. Infected rabbits will usually die due to liver failure or a clotting disorder. There are three ways in which infection can manifest:
- Peracute – the rabbit is found dead within a few hours of being apparently normal – this is the most common presentation.
- Acute – affected rabbits present with lethargy, fever and increased respiratory rate. These animals usually die within 12 hours due to haemorrhage and blood may be seen at any orifice.
- Subacute – rabbit shows mild signs from which they recover and then become immune to further RHDV infection
In 2010 there was an outbreak of RHDV in France in which 25% of vaccinated rabbits died, there was also a similar outbreak seen in wild rabbits. Samples were taken from these rabbits and it was discovered that the outbreak was due to a new variant strain of RHDV, known as RHDV2. RHDV2 cases were also confirmed in Italy in 2011 and in the UK in 2013, although retrospective studies show that RHDV2 is likely to have been in the UK since 2010. The infection has potential to cause devastating effects to the wild rabbit population because it affects rabbits of all ages, and unlike with the original strain (RHDV) rabbits younger than 4 weeks of age have no natural immunity to RHDV2 and so young suckling rabbits can be affected.
RHDV2 causes mortalities 3-9 days after infection, therefore running a longer course than that of the classical RHDV strain. Subacute and chronic infections are more common in RHDV2 and more rabbits survive. Clinical signs seen in RHDV2 tend to be systemically ill rabbits, with weight loss, appetite loss and jaundice due to liver failure. RHDV and RHDV2 diagnosis is usually made at post mortem. There is no specific treatment for affected rabbits and the majority will die quickly. Supportive care is indicated but these rabbits can be infectious to others and their prognosis is poor.
In the UK we recommend routinely vaccinating rabbits against RHDV, this is an annual vaccination that is combined with a Myxomatosis vaccine. This vaccine only forms immunity to the classical strain of RHDV, meaning that even our currently vaccinated rabbits are still at risk of this new variant RHDV2. Vaccines against RHDV2 have been developed in Europe and these vaccines can be imported into the UK to vaccinate pet rabbits against RHDV2. We are pleased to say that one such vaccine should be available in the UK from the middle of June 2016. Rabbits will still need their regular vaccinations to cover against Myxomatosis, but to cover them against RHDV2 they will need a further annual vaccine at least 2 weeks later.
For more information regarding the new variant of RHDV2 please feel free to contact our vets. If you would like to get your rabbit vaccinated against the new variant strain please contact our reception on 01235 814991 or 01491651379 to register your interest so that we can ensure a sufficient vaccine supply when they become available.
Laura Bateman BVMedSci (Hons) BVM BVS MRCVS
DATE FOR YOUR DIARY!
Vet Laura is holding a free talk on general rabbit husbandry, covering everything you need to know to keep your rabbit happy and healthy, on Thursday 23 June 2016, 7.30pm, at our Didcot branch. Call 01235 814991 to book your place. All are welcome, although places are limited.