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Key points about RHD

  • Rabbit haemorrhagic disease (RHD) is also known as viral haemorrhagic disease (VHD).
  • RHD is a cause of sudden death in pet rabbits. It can cause multiple deaths in multi-rabbit households. There may be little or no warning that a rabbit is about to die.
  • The virus that causes RHD is a calicivirus. Caliciviruses readily mutate and several strains and variants exist. 
  • The original genotype of RHD virus (RHDV1) caused an outbreak in the UK in the 1990's, which was eventually controlled by vaccination
  • A new genotype of RHDV (RHDV2) emerged in 2010 and has superseded RHDV1 in many parts of the world. It is the cause of a current epidemic RHD in the UK
  • Unlike RHDV1, RHDV2 can affect rabbits under 4 weeks old. Baby rabbits can be vaccinated.
  • Little is known about carrier status of RHDV2. 
  • A definitive diagnosis of RHD is difficult in the live animal. There is no reliable blood test. There is no treatment other than palliative care.
  • Diagnosis is usually made after death. Internal post-mortem examination may or may not show definitive changes, but microscopic examination of the liver and other organs is usually diagnostic. Histopathology also provides information about alternative causes of sudden death.
  • PCR testing for RHDV using liver tissue confirms the diagnosis and identifies the genotype. False-positive results are unlikely but false-negatives occasionally occur.
  • 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. 
  • RHDV2 is endemic in the wild rabbit population. The RHD virus can survive in faeces from infected rabbits, scavengers or insects and contaminate shoes or clothing of people that walk in through areas inhabited by wild rabbits.
  • Infected faeces from scavengers, such as foxes or crows, and flying insects can spread infection and contaminate gardens.
  • Food grown in areas where there are infected rabbits (hay, forage, vegetables) may be contaminated.
  • Vaccination is the only way to protect rabbits from RHD
  • Filavac (Ceva Animal Health) and Eravac (Hipra Laboratories) are inactivated adjuvanted vaccines specifically against RHDV2 that are licensed for use in the UK. Filavac is effective against both RHDV1 and RHDV2. Eravac is only effective against RHDV2. Neither offers protection against myxomatosis.
  • Nobivac Myxo-RHD is a recombinant vectored myxomatosis/RHD vaccine although it is not protective against RHDV2. In May 2020, a new recombinant vectored vaccine, Nobivac Myxo-RHD PLUS became available in the UK and Europe. It is effective against both RHDV1, RHDV2 and myxomatosis
  • Switching vaccines from Nobivac Myxo-RHD to Nobivac Myxo-RHD PLUS is complicated by pre-existing immunity to the myxomavirus vector. Priming immunity from additional inactivated vaccination (Filavac or Eravac) is required.