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Rabbit Hemorrhagic Disease (RHD)
Also known as:
Rabbit Viral Hemorrhagic Disease (RVHD), Rabbit Calicivirus Disease (RCD), Viral Hemorrhagic Fever, Viral Necrotizing Hepatitis
ALERT: TWO UNRESOLVED OUTBREAKS OF RABBIT HEMORRHAGIC DISEASE ARE CURRENTLY ONGOING IN CUBA, BEGINNING MAY 18, 2010. BE VERY CAREFUL IF YOU HAVE ANY DEALINGS WITH RABBITS, RABBIT PRODUCTS OR ANY RABBIT MATERIALS, INCLUDING FROZEN MEAT OR PELTS, WITHIN CUBA OR COMING FROM CUBA.
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Rabbit Hemorrhagic Disease (RHD or RVHD) is one disease which I pray to God never reaches my barn.
What is it?
RHD is a devastating viral disease that will quickly kill 90% or more of your rabbit herd. The virus incubates over 1-3 days, and then you start seeing dead rabbits for no obvious reason in your rabbitry. In rabbit colonies, you may see 90% sick rabbits and when it’s all over, 100% are dead. What are the signs and symptoms?
The disease presents itself in three forms, depending on the virulence of the virus strain and the health and age of the rabbits. The virus is bad news, however some strains are not as potent as others, depending on the area of the globe in which you live: - PERACUTE: (very acute and violent): No signs or symptoms - just a dead rabbit very suddenly. And then more dead rabbits, because it is exceedingly contagious.
- ACUTE: The rabbit goes off its feed, is lethargic and has to strain to breathe. Body temperature soars to 105 - 106F, then begins cooling just before the rabbit dies.
- SUBACUTE: Bloody nasal discharge, tightness and arching in the back and noisy respiration as the rabbit struggles to breathe. If you see these symptoms, the rabbit may die within 2-3 hours. In some rabbits under 4 months of age, the rabbit may manage to recover and then become immune.
But despite being immune, such a rabbit is a likely to become an asymptomatic carrier of the virus, as the germs are shed in the urine and excreta for at least a month, and the animal could be a carrier of the virus for much longer.
What causes Rabbit Hemorrhagic Disease?
The causative agent is a virus known as a calicivirus. The disease was first reported in China in 1984, and has since been reported in most of Europe, parts of Asia, and Mexico (now eradicated). The United States has experienced several isolated outbreaks. See the map, provided by APHIS, which is dated 2000. In Australia in 1995, after a laboratory accident that released the calicivirus into the environment, 10,000,000 rabbits died inside of 8 weeks.  The only good piece of news about the calicivirus is that humans are not susceptible to it.
How does the disease spread?
The virus is sticky! It spreads very easily by direct contact, biting insects, handling infected rabbit meat and by-products, and touching any animate or inanimate object on which the virus sticks, such as food and water crocks and your own clothes and hands, carrying cages, etc. The virus is hardy - it can outlast heat and cold easily. It is highly contagious and easily spread. What will a necropsy show?
Tracheal hemorrhages, pulmonary edema (water-logging of the lung tissues) and congestion, petechiae (tiny hemorrhages) on the myocardium, kidney, and spleen, and extensive hepatic necrosis (liver gangrene). How can I tell if my rabbits are dying from Rabbit Hemorrhagic Disease?
You can make an initial tentative diagnosis based on the rapidly fatal infection and what your naked eye can see on a necropsy exam. But with such a virulent disease, it is vital to call your vet or the USDA so they can arrange for a VHD-specific PCR (Polymerase Chain Reaction) - the proving method used to duplicate and then identify the calicivirus definitively - and either confirm or rule out your initial tentative diagnosis. If positive, the authorities will also want to identify where the calicivirus came from and how it got to your herd. Is there anything I can do to treat my rabbits?
No, there is no effective treatment. What should I do if I suspect Rabbit Hemorrhagic Disease?
If your rabbits start dying for no good reason, you MUST immediately isolate your herd. - If necropsies support a diagnosis of RHD, kill any remaining animals in your rabbitry. This is the only way to prevent the spread of the infection.
- Immediately report the outbreak to the state veterinarian, and to the USDA. (I would probably also communicate with the vets in my area to give them a heads-up.) Double-bag and freeze some carcasses for disease confirmation.
- Careful sanitation and disinfection are imperative to halting or limiting the spread of Rabbit Hemorrhagic Disease, as is the maintenance of a closed herd.
- Disinfect everything that has come into contact with your rabbits.
- In some areas of the world where the disease is endemic in native rabbit populations, killed virus vaccines can provide some modicum of protection. (It is believed that the cottontails native to the New World are NOT susceptible to RHD, however domestic rabbits are of the same genus and species as rabbits native to Europe, which are susceptible, and which carry the infection.)
The Rabbit Industry Council has prepared an excellent handout on RHD in PDF form. Click on the third link under References (below), or
Get the Rabbit Hemorrhagic Disease Info Flyer by clicking here
.
References:
AN ISOLATED OUTBREAK OF RABBIT HEMORRHAGIC DISEASE OCCURRED IN PINE COUNTY, MINNESOTA IN APRIL, 2010. PLEASE READ ON IF YOU ARE AN OWNER OF ONE OR MORE RABBITS, LIVE ANYWHERE NEAR MINNESOTA, OR GO TO RABBIT SHOWS.
Here is the Rabbit Hemorrhagic Disease announcement by the RABBIT INDUSTRY COUNCIL, quoted verbatim: Rabbit Viral Hemorrhagic Disease (RVHD) On May 3, 2010, we were notified of a small occurrence (25 rabbits) of Rabbit Viral Hemorrhagic Disease (RVHD) in Pine County, MINNESOTA. All rabbits on the premises have died or been euthanized, and at this time there is no further known spread. However, as this 'index premises' was one which collected rabbits from multiple sources, we do not know the initial source of the disease. Should you panic? NO! While frightening in its tenacity and ease of transmission, this disease can be managed and limited in spread by common precautions. It should never be treated lightly or disregarded. We STRONGLY encourage those in Minnesota and the surrounding area to think carefully about any unexplained deaths in their herds and to take the appropriate steps for accurate diagnosis should symptoms and signs indicate any possibility of RVHD. If you have any doubts, contact your State Veterinarian for assistance--or contact the Rabbit Industry Council at 530-534-7390 or RIC@cncnet.com. ***Please see further details below** We also STRONGLY encourage all shows and exhibitors to use an appropriate disinfectant (see below) on all coops, carpets, and equipment. If you are uncertain of your herd health status, please stay home until you get it straightened out. A PDF with all this information is available at http://www.showbunny.com/RVHD/InfoSheet_06-13-05.pdf. While the document is not yet updated to the current outbreak as yet (pending further, more detailed information), it is accurate and highly useful regarding prevention, management, and reporting of this deadly disease.
*****MINNESOTA OUTBREAK INFORMATION*****
On 4-22-10, a report was made to the OIE which noted that beginning in early February of 2010, rabbits at a facility in PINE COUNTY, MINNESOTA which collected rabbits for use as food at a wildlife rehabilitation center began to die at a startling rate, with 20 dying initially. This was thought to be due to feed contamination, but as further rabbits brought onto the property also died rapidly without clinical disease, a sample was submitted to a private laboratory for analysis.WE CANNOT PRAISE THIS FACILITY ENOUGH FOR TAKING THIS STEP! It is vital that we all investigate unexpected deaths, especially multiple deaths, with diligence and care. The sample was suspected to be positive for RVHD and further testing was done by the Foreign Animal Disease Diagnostic Laboratory and found to be definitively positive on enzyme-linked immunoassay testing for Rabbit Hemorrhagic Disease Virus. The property was then thoroughly decontaminated and any remaining rabbits euthanized. Free ranging rabbits in the area are being trapped and surveilled for signs of the disease. (While native species are not susceptible, it is not known if there are feral domestics in the area.) As of this point in time, this is the limited information we have. We're working on re-establishing contacts within USDA/APHIS to be able to bring you more and more detailed information as soon as possible.
(End quote from Rabbit Industry Council)
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