Rabbit Hemorrhagic Disease Virus, also referred to as RHD or RHDV, is a fatal viral infection in rabbits. RHDV Type 2 (RHDV2) was first identified in a feral domestic rabbit colony in the Milwaukie, Oregon area on Tuesday, March 23, 2021, followed by domestic and wild detections in La Pine, Oregon from April to June of 2021. This disease is highly contagious among domestic rabbits and has high mortality rates in rabbit colonies.
Unlike RHDV, RHDV2 can infect native rabbit and hare species.
Rabbit Hemorrhagic Disease Virus (RHDV) cases in Oregon
Symptoms of RHD in domestic rabbits may include:
- Acute/rapid death
- Fever
- Lethargy
- Lack of appetite
- Congested membranes around the eyes
- Nervousness
- Lack of coordination
- Excitement or paddling
- Difficulty breathing
- Bloody, frothy nasal discharge at death
Prevention
The best way to protect your rabbits is to practice strong biosecurity practices. There is no cure or treatment for RHD and although a vaccine is available, its efficiency at protecting rabbits is not well know. Use the documents below in the resources for information on biosecurity and sanitation practices to protect your rabbits from RHD.
There is now a vaccine for RHDV2 licensed for use in the US. Some Oregon veterinarians have begun offering the domestically produced vaccine to clients. The vaccine is currently available under a limited license which requires administration by a veterinarian under a valid veterinary-client-patient relationship. The vaccine is not approved for use in feral or wild rabbits.
Frequently Asked Questions
RHD is a highly contagious, fatal viral disease in rabbits caused by multiple virus strains. It is an internationally reportable disease to the world organization for animal health (OIE).
For immediately reportable diseases and conditions (e.g., unidentified vesicular disease), in most cases, we want reporting prior to testing since ODA can help expedite shipping/testing and can generally cover the cost when testing is necessary. Additionally, for many of those situations, specific testing will be required and we want to help ensure proper samples are taken and laboratory submission protocols are followed.
Rabbit hemorrhagic disease is caused by rabbit hemorrhagic disease virus (RHDV), a member of the genus Lagovirus and family Caliciviridae. There are many strains of RHDV, and three major viral subtypes: RHDV (“classical RHDV”), the antigenic variant RHDVa, and the recently emerged virus RHDV2 (also called RHDVb). Related lagoviruses, called rabbit caliciviruses, circulate in healthy rabbits. These viruses can confer varying degrees of cross-protection to RHDV.
While most rabbit caliciviruses do not appear to cause any illness, two potentially pathogenic strains have been reported. One virus identified in the U.S. (proposed name “Michigan rabbit calicivirus”) was isolated from an outbreak that resembled rabbit hemorrhagic disease, although an attempt to reproduce the disease in experimentally infected rabbits resulted in little or no illness. A related strain, the Ashington strain of rabbit calicivirus, was recovered from dead wild rabbits during an outbreak in Europe.
We understand that sometimes testing will be conducted which results in an immediately reportable disease being diagnosed prior to ever having reported that disease as suspected. Please just call ODA when you do get positive results, we want to ensure we help veterinarians and animal owners with any required biosecurity needs and any potential regulatory response as/if required. Depending on disease and situation circumstances, there may not be any further regulatory requirements beyond reporting.
There are many strains of the RHD virus, but three are of most concern. RHD Type 1 has two forms, RHDV and RHDVa. RHD Type 2 has just one form, RHDV2. The two forms of Type 1 are quite similar and their vaccines are cross-protective. They tend to not affect young bunnies but have a very high mortality rate for adult rabbits. RHDV2, on the other hand, seems less deadly than the Type 1 strains, but affects all ages of rabbits. The RHDV2 vaccine only protects against that type. All RHD virus types are in the viral family Caliciviridae and genus Lagovirus.
Yes. You can submit a monitored disease report online via this online reporting form:
https://data.oda.state.or.us/fmi/webd/AH_Online?script=Startup¶m=Disease
Only laboratory tests can confirm a diagnosis of RHD. However, RHD should be suspected if a rabbitry experiences illness in most/all rabbits, high fevers, poor appetites, depression, inactivity, bloody discharges, seizures, and/or sudden death. Call your veterinarian right away if you have any concerns about your rabbit's health. Usually RHDV2 is associated with mass morbidity (illness) and mortality (death) in a colony or herd.
The main reason for these adjustments was the numerous requests to ODA from veterinarians and animal industries. In recent years, there have been several situations where animals diagnosed with an infectious disease were knowingly moved, leading to additional exposures and new cases of the disease. The desire to have the diseases made immediately reportable was centered around high-risk situations (e.g., large barns or shelters) where ODA can help implement biosecurity and quarantines as needed. For lower risk situations, there may not be any regulatory action taken beyond taking the report.
Rabbit hemorrhagic disease spreads between rabbits mostly by ingestion and inhalation of the virus. The virus is present in urine and feces from infected rabbits, so contaminated bedding, food or forage can be a source of infection. The virus can be moved from place to place mechanical vectors and fomites (flies, predators, scavengers, feral domestic and wild rabbits, vehicle tires, clothing, footwear, cages, equipment, and wind and water movement).
This will depend on the specific disease and situation. For most diseases, we have a fair amount of latitude in terms of how we respond, and for many diseases, we will defer to a joint risk assessment of the case with the attending veterinarian. For example, if the case occurs on a fairly isolated farm and the risk of spread beyond that property is minimal, we often may not take any further action beyond recording the case. If the case occurs in a larger/busier facility, or in an animal where compliance with biosecurity/isolation is of concern, we can work with you and the owner to obtain testing as appropriate and then take regulatory action as/if needed. This may include quarantine, monitoring, and further testing.
RHD is not a zoonotic disease and there is no public health significance. RHD is specific to rabbits. Dogs, cats, and other pets cannot contract the disease, but can transport the virus just like vehicles, shoes, and equipment can.
These are common questions regarding endemic diseases and opportunistic pathogens. The short answer is yes, please report every new case/infection even if the animal is not showing clinical signs. We want all cases reported so that we can build a publicly available dashboard for veterinarians to see case numbers by county (of all reportable diseases in Oregon). We are relying on the clinical judgement of veterinarians to identify and report infections with reportable diseases. If an antibody test suggests previous exposure rather than current infection, this does not necessarily need to be reported but we will still accept a report. When in doubt, report it.
Exposure to the virus does not necessarily mean a rabbit is infected with the virus. Some rabbits will just be exposed; others will be exposed and become infected and either die or recover. Recovering rabbits will develop antibodies to the virus and become resistant to related calicivirus strains for an unknown period. Infected rabbits can “carry" or shed the virus for over a month, perhaps up to four months (when experimentally infected); they are not believed to be infected and shed for life.
The RHD virus was first identified in China in the early 1980s. Outbreaks occur periodically throughout the world and continually in some countries but have been quite rare in North America. Since 2019 RHDV2 has been an emerging disease issue in North America; British Columbia experienced outbreaks of RHDV2 in 2018-2019, primarily on Vancouver Island. Isolated cases were reported in OH in 2018 and NY in 2020. WA had an outbreak in 2019-2020. A multistate outbreak in NM, AZ, CA, CO, TX, NV and UT started in 2020 and is ongoing. Mexico has also confirmed detection of RHDV2 virus in 6 northern states. The source of the recent RHDV2 outbreaks has not been identified.
For chronic diseases, if the case has already been reported, we do not need reporting of continued positive results that are presumed to be the same infection (or part of the same outbreak already reported in a herd). Similarly, if an animal was diagnosed with a reportable disease through laboratory tests submitted by another Oregon veterinarian, you do not need to report that case (since the previous veterinarian was required to do so by law). However, if an animal/herd clears a disease and is later reinfected, that new infection should be reported. We are relying on the best clinical judgement of veterinarians, and when in doubt, report it.
The RHDV2 viruses in the North American outbreak are phylogenetically different. The NVSL Foreign Animal Disease Diagnostic Laboratory completed full genome sequencing and analysis of rabbit hemorrhagic disease virus 2 (RHDV2) isolates detected in the United States from 2018 through 2020, including from the ongoing outbreak in the southwestern United States.
The phylogenetic analysis indicates isolates cluster by geographical region (NY, OH, and WA are all different from SW states). The most recent southwestern isolates form a single genetic cluster suggesting that the outbreak of RHD in these states was caused by the introduction of a single genetic isolate into the region; this virus is responsible for the disease in both wild rabbits and hares and domestic rabbits.
If you clinically diagnose a reportable disease using the supportive diagnostics available to you and a physical exam, then please report that case.
The virus can survive for long periods outside the host. Environmental temperature, humidity, and protection by organic material are important factors in virus survival. Viable virus has been detected for as long as 105 days on a fomite at room temperature and in decaying tissue of infected carcasses for up to 90 days; it persists in chilled or frozen rabbit meat. The virus can remain viable for 22-35 days at 72°F. It survives freeze-thaw cycles. Pelts from dead wild or domestic rabbits in premises or geographic areas during an RHDV outbreak should not be processed, transported or sold.
Both IDEXX and Antech automatically report reference laboratory test results to ODA for many monitored diseases. At this time, no other Oregon laboratories automatically report monitored disease results to ODA. We are in communication with the main laboratories that serve Oregon veterinarians and hope to have additional laboratories that will automatically report monitored diseases.
When a reference laboratory automatically reports positive results for any monitored disease to ODA, that fulfills the veterinarian's responsibility to report those results. Positive in-house lab results must still be reported to ODA by the veterinarian or veterinary practice within 15 days, even if the results are uploaded into an online laboratory system, because those systems do not share data with ODA. (See the Searchable Disease List table for specific diseases that are automatically reported.)
Note: Immediately reportable diseases must always be reported to ODA by veterinarians or the veterinarian's office via phone (503-986-4711), even if a laboratory sends results to ODA.
Veterinarians practicing in Oregon are legally required to report certain diseases and abnormalities only to ODA. ODA forwards positive results to partner agencies and select organizations, which may satisfy a veterinarian's desire to report to additional organizations. Currently, ODA forwards results of interest to the Oregon Health Authority (OHA), the Oregon Department of Fish and Wildlife (ODFW), and the Equine Disease Communication Center (EDCC).
Note: Laboratories (not individual veterinarians) are required by OAR 333-018-0017 to report certain diseases of zoonotic concern directly to the OHA Public Health Division.
Please reach out to the Animal Health Program at 503-986-4680 or animalhealth@oda.oregon.gov and we will do our best to answer your questions.
If you notice any of the above symptoms in your rabbits notify the Oregon State Veterinarian immediately!
For domestic rabbits:
Oregon State Veterinarian
AnimalHealth@oda.oregon.gov
Phone: 503-986-4711
For wild rabbits:
Oregon Department of Fish and Wildlife
Phone: 1-866-968-2600 Resources
ODA Resources
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Biosecurity Guidance Document -English,
Español
Rabbit owners and commercial operations should work with their veterinarian to identify their biosecurity risk factors.
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Biosecurity Steps Infographic -
English,
Español
8 Biosecurity steps to help protect your animals from disease. -
Disinfectant Selection -English,
Español
There are currently no disinfectants that specifically list RHDV2, on their label. The U.S. Environmental Protection Agency (EPA) has identified products that are effective against similar viruses and are believed to be effective against RHDV2.
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Infographic Poster -
English,
Español
ODA poster with information and guidance on Rabbit Hemorrhagic Disease (RHDV). Includes contact information for reporting. -
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