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Key points about RHD

  • The virus that causes  Rabbit (or Viral) Haemorrhagic Disease (RHD or VHD) is a calicivirus. Caliciviruses readily mutate and several variants exist. 
  • The original strain RHDV1 caused a an outbreak in UK in the 1990's
  • A new variant, RHDV2, is causing a major outbreak of RHD in UK at the present time
  • RHDV2 is not prevented by Nobivac Myxo-RHD vaccination. Additional vaccination is required. Filavac is a vaccine that is licensed for use in UK and protects rabbits against RHDV1 and RHDV2.
  • Vaccination with both Nobivac Myxo-RHD and Filavac is required to protect rabbits against Myxomatosis, RHDV1 and RHDV2. An interval of two weeks between vaccinations is advised and both vaccines require annual boosters.
  • Baby rabbits can be vaccinated with Filovac at 4-5 weeks of age but need a booster at 12 weeks and annual vaccination thereafter.
  • The RHDV2 is less virulent than the original strain.  It has a lower and variable mortality rate but can affect rabbits under 4 weeks old. 
  • Although rabbits may die suddenly from RHDV2, some can recover and others may show no clinical signs at all.
  • It is not known how long a rabbit that has recovered from RHD remains infectious. A period of 30 days has been suggested. Little is known about carrier status of RHDV2. 
  • The RHD virus is very difficult to kill. It can survive outside the body and is resistant to temperature changes. It can survive at 50 degrees centigrade for an hour i.e some washing machine cycles. 
  • RHD and its variants are easily spread. The virus can survive in the digestive tract of animals that feed on carcasses of rabbits that have died. For example, faeces from crows, foxes and flying insects can infect rabbits
  • In the UK, definitive diagnosis of RHD is difficult in the live animal.  There is no reliable blood test. Diagnosis is usually made after death. Post-mortem signs may or may not show definite signs. Microscopic examination of the liver and other organs will show signs that are highly suggestive.
  • Confirmation of the diagnosis is RHDV1 or RHDV2 is made from PCR testing on the liver
  • A research project is underway that pays for histopathology and, if indicated, PCR testing in rabbits that die unexpectedly. Certain criteria exist. More information can be found here.
  • The way RHDV is spread in the pet rabbit population is unclear. In order to gather and share information, a questionnaire for owners of rabbits that have died is available. The results are published each month on this website.