Rabbit Hemorrhagic Disease (RHD) is a deadly viral illness that affects rabbits. This highly contagious condition spreads rapidly among both domestic and wild rabbit populations. Understanding RHD is important for rabbit owners and the public.
Understanding Rabbit Hemorrhagic Disease
RHD is caused by a type of calicivirus that can persist in the environment. Two primary strains have been identified: Rabbit Hemorrhagic Disease Virus 1 (RHDV1) and Rabbit Hemorrhagic Disease Virus 2 (RHDV2). RHDV1 primarily affected adult European rabbits.
RHDV2, a more recently identified variant, emerged around 2010 and has become more widespread. This strain can affect rabbits of all ages and breeds, including hares and cottontail rabbits. RHD is a systemic disease characterized by liver damage and internal bleeding.
Recognizing the Signs and How It Spreads
Rabbits infected with RHD may show a range of symptoms, though sudden death without prior signs is a common outcome. Other signs include fever, lethargy, and a loss of appetite. Respiratory distress, such as difficulty breathing, and neurological signs like convulsions, may also occur. Bleeding from orifices, such as the nose, mouth, or rectum, is a frequent indicator due to internal hemorrhaging.
Symptoms can vary, especially with RHDV2, and may be subtle or absent before a rapid decline. The incubation period for RHDV1 is typically 1-2 days, while for RHDV2 it ranges from 3-9 days. The virus spreads primarily through direct contact between infected rabbits, but it can also be transmitted indirectly through contaminated objects like cages, food bowls, and bedding. People can inadvertently spread the virus on their clothing, shoes, and hands. Insects, particularly mosquitoes, and even predators or scavengers can also carry the virus, which is highly resilient and can remain viable in the environment for several months.
Protecting Rabbits from RHD
Vaccination is the most effective method for preventing RHD. Vaccines protect against both RHDV1 and RHDV2 strains and can be administered to rabbits from 10 weeks of age, with annual boosters recommended to maintain immunity. Protection becomes effective within seven days of vaccination. While vaccines offer significant protection, practicing good hygiene remains important as vaccines are not 100% effective.
Biosecurity measures are also important for rabbit owners. This includes regularly cleaning and disinfecting cages, dishes, and other accessories. Washing hands thoroughly after handling rabbits is advised, and new rabbits should be isolated for about 30 days before being introduced to other animals. Controlling insect vectors through methods like mosquito screens or rabbit-safe repellents can help reduce exposure. Avoiding contact with wild rabbits and exercising caution with hay or feed sources that might have been exposed to the virus are additional preventive steps, as there is no specific treatment for RHD once a rabbit contracts the disease, making prevention the primary focus.
Impact on Rabbit Populations
RHD has a significant impact on both domestic and wild rabbit populations, causing high mortality rates. RHDV2 has been confirmed in various wild species, influencing wildlife management and conservation efforts. The disease can also have economic consequences for commercial rabbitries due to high mortality rates. Community awareness and widespread prevention efforts are important for maintaining overall rabbit health and mitigating the broader effects of this disease.