Viral Haemorrhagic Disease (VHD) of rabbits is an acute and usually fatal disease which causes acute necrotic hepatitis (liver disease) in rabbits over 2 months of age. It is caused by a Calicivirus and is similar to European Brown Hare Syndrome which has been present in Europe since 1980.
VHD is a very contagious disease which can be spread directly between rabbits but can also be carried by birds, flies and other insects. Infection occurs via the oral, nasal and conjunctival routes. Unfortunately the virus is very stable in the environment and can survive for up to 105 days at normal room temperature. Once a rabbit is infected with VHD the disease is usually incubated for about 1-3 days. Once the rabbit becomes sick and has a fever, death usually follows in 12- 36 hours.
Signs of VHD in rabbits include elevated rectal temperature (>41 degrees centigrade), lethargy, loss of appetite, convulsions, collapse, vocalization, in-coordination, difficulty breathing and a bloody discharge from the nose. Because the disease quickly causes death few of these signs may be noticed. In 5 to 10% of rabbits the disease takes a more chronic course and here the signs include jaundice, lethargy and weight loss. Rabbits with the chronic form of the disease often die from liver failure within 1 to 2 weeks.
If VHD is suspected there are tests which can be undertaken at Veterinary Laboratories to confirm this, ( other diseases of rabbits may cause similar signs). The most reliable test is electron microscopy of frozen liver samples to search for the viral particles. Testing for antibodies is perhaps unreliable due to an apparent strain of VHD which causes antibody production without causing the disease. Post mortem examination of rabbits which have died from VHD will reveal haemorrhages throughout the liver and other internal organs.
This disease can be prevented by vaccinating your rabbit against VHD using a vaccine called Cylap. This vaccine is a killed vaccine and is very effective. Rabbits may be vaccinated using Cylap from 14 weeks of age and they need to have a booster vaccination every year. Rabbits should not have the Myxomatosis vaccine at the same time but should have this vaccine at least 2 weeks before or after the Cylap.