Rabbit Hemorrhagic Disease (RHDV2): Prevention and Outbreak Management

Rabbit hemorrhagic disease virus 2 (RHDV2) is a highly contagious calicivirus that causes acute, often fatal hepatitis in domestic and wild rabbits and hares. This article provides rabbit owners and veterinary professionals with evidence-based guidance on virus strains, transmission routes, clinical signs, vaccination protocols, biosecurity measures, and outbreak management procedures. The information is drawn from peer-reviewed research and official veterinary sources to support practical decision-making on farms and in veterinary practice.

At a Glance

Virus Strains and Epidemiology

Rabbit hemorrhagic disease virus 2 (RHDV2, genotype GI.2) was first identified in France in 2010 and has since spread globally, causing significant mortality in both domestic and wild lagomorph populations. A review of global detections from 2010 to 2023 documented RHDV2 in multiple countries across Europe, North America, Africa, Asia, and Australia, affecting European rabbits (Oryctolagus cuniculus) as well as several hare species (Lepus spp.) [10]. The virus is genetically distinct from classical RHDV (GI.1), which emerged in the 1980s.

RHDV2 is a recombinant virus, with evidence suggesting that the first identified strain arose from recombination between a non-pathogenic lagovirus (GI.3P) and a pathogenic RHDV2 (GI.2) [13]. This recombination event is considered a key mechanism in the emergence and evolution of RHDV2. Continued recombination poses ongoing risks, as demonstrated by the detection of a new RHDV2 variant in China in 2025 that showed evidence of recombination between North American GI.2 strains and local GI.1a strains, causing 70-80% mortality in domestic rabbits [13].

The virus affects a broader host range than classical RHDV, including young rabbits (which were previously resistant to classical RHDV) and multiple hare species. In Ireland, the first outbreaks of RHDV2 in 2019 affected wild Irish hares (Lepus timidus hibernicus), raising conservation concerns [11]. In the United States, detections of RHDV2 in wild lagomorphs following the 2020 outbreak have been documented across western states, indicating sustained environmental circulation [7]. A 2022 study on early pathogenesis confirmed that RHDV2 initially replicates in the liver, causing severe hepatocellular necrosis and apoptosis [8].

Transmission Routes

RHDV2 spreads through multiple pathways that rabbit owners and veterinarians must understand to implement effective control measures.

Direct Contact

Infected rabbits shed the virus in all body secretions and excretions, including urine, feces, respiratory secretions, and blood. Direct contact between infected and susceptible rabbits is the most efficient transmission route. The virus can be shed before clinical signs appear, making early detection difficult. Mortality rates in naive populations can reach 70-80% as observed in Chinese farm outbreaks [13].

Indirect Transmission

The virus is extremely stable in the environment and can survive on contaminated surfaces, feed, bedding, equipment, and clothing for months under favorable conditions. Fomites such as boots, tools, vehicles, and feeding equipment are common vectors. Insects, including flies and mosquitoes, can mechanically transmit the virus between facilities. Contaminated feed and water sources represent significant risk factors, particularly on commercial farms.

Airborne Transmission

RHDV2 can be transmitted over short distances through aerosolized particles, especially in enclosed spaces with poor ventilation. This route is particularly relevant in indoor rabbitries where animals are housed in close proximity.

Wildlife Reservoir

Wild lagomorph populations can serve as reservoirs for RHDV2, maintaining the virus in the environment and posing ongoing risk to domestic rabbits. The 2020 outbreak in the western United States demonstrated how the virus can spread rapidly through wild populations and subsequently infect domestic rabbits [7]. A 2024 review of detections following that outbreak confirmed sustained circulation in wild lagomorphs across western states [7].

Clinical Signs and Pathogenesis

RHDV2 causes acute, often fatal hepatitis in susceptible rabbits. The incubation period ranges from 1 to 5 days, with death occurring 12 to 72 hours after the onset of fever.

Peracute Form

Many rabbits die without showing any clinical signs. Owners may find dead animals that appeared healthy the previous day. This peracute form is common in naive populations with high mortality rates.

Acute Form

Rabbits with acute disease may exhibit:

• Fever (temperature above 40°C or 104°F)
• Lethargy and depression
• Anorexia
• Respiratory distress, including tachypnea and dyspnea
• Neurological signs such as ataxia, paddling, opisthotonos, or seizures
• Hemorrhages from the nose, mouth, or rectum
• Cyanosis of mucous membranes
• Abdominal distension due to liver enlargement

Subacute and Chronic Forms

Some rabbits, particularly those with partial immunity or those infected with lower doses, may develop subacute disease with milder signs and survive. These animals can shed virus for weeks and serve as sources of infection for others.

Pathogenesis

Early pathogenesis studies indicate that RHDV2 initially replicates in the liver, causing severe hepatocellular necrosis and apoptosis [8]. The virus targets hepatocytes and Kupffer cells, leading to fulminant hepatitis, disseminated intravascular coagulation, and multi-organ failure. The characteristic hemorrhages result from coagulation abnormalities and vascular damage.

Diagnosis

RHDV2 cannot be diagnosed based on clinical signs alone, as other diseases can present similarly. Laboratory confirmation is essential.

Sample Collection

Veterinarians should collect liver tissue, spleen, and blood from deceased rabbits for testing. For live animals, whole blood in EDTA or serum can be used for PCR testing. Samples should be refrigerated and shipped to a diagnostic laboratory as soon as possible.

Laboratory Tests

• PCR (polymerase chain reaction): The most sensitive and specific test for detecting RHDV2 RNA in tissues, blood, or feces. Real-time RT-PCR can differentiate RHDV2 from classical RHDV.
• ELISA (enzyme-linked immunosorbent assay): Detects antibodies against RHDV2 in serum, useful for surveillance and vaccine response monitoring.
• Hemagglutination test: Detects virus in liver homogenates. RHDV2 may have lower hemagglutination activity than classical RHDV.
• Histopathology: Liver sections show severe acute hepatic necrosis with minimal inflammatory response.
• Electron microscopy: Visualizes calicivirus particles in liver tissue.

Differential Diagnoses

Conditions that may mimic RHDV2 include:

• Classical RHDV (GI.1)
• Tularemia (Francisella tularensis)
• Pasteurellosis (Pasteurella multocida)
• Hepatic coccidiosis (Eimeria stiedae)
• Toxicity (e.g., aflatoxin, lead)
• Heat stroke

Vaccination Protocols

Vaccination is the most effective tool for preventing RHDV2 in domestic rabbits. Several vaccine types are available, with recombinant VP60 vaccines showing strong efficacy.

Available Vaccine Types

Recombinant VP60 vaccines: These vaccines use baculovirus expression systems to produce virus-like particles (VLPs) composed of the VP60 capsid protein. They are non-infectious and safe for use in rabbits. Studies have demonstrated that these vaccines induce both humoral and cellular immune responses [17]. A 2024 study found that a baculovirus recombinant vaccine provided durable immunity against RHDV2 challenge [6].

Inactivated vaccines: Traditional inactivated vaccines are produced by growing the virus in cell culture and inactivating it with chemicals. These vaccines require adjuvants to enhance immunogenicity. A 2024 study evaluated the comparative effect of aluminum hydroxide gel and Montanide ISA 70 adjuvants in locally prepared RHDV2 vaccines, finding that adjuvant choice affects vaccine potency and protection [18].

VLP-based vaccines: Virus-like particle vaccines produced in insect cells (Sf9) have shown strong protection. A 2026 study demonstrated that a VLP vaccine based on the prevalent Chinese RHDV2 strain provided full protection against challenge with different clinical RHDV2 strains for at least 180 days [14]. Another study from 2025 showed that a VLP vaccine protected rabbits against a new recombinant RHDV2 variant [13].

Vaccination Schedule

The specific vaccination schedule depends on the vaccine product used. General guidelines include:

• Initial vaccination: Rabbits can be vaccinated from 4-5 weeks of age, depending on the product.
• Booster vaccination: A second dose is typically given 3-4 weeks after the first.
• Annual revaccination: Most vaccines require annual boosters, though some studies suggest protection may last up to 12 months [15].

A 2026 study of a new commercial recombinant RHDV2 VP60 vaccine found that vaccinated rabbits showed higher antibody levels against RHDV2 than controls at 7 days post-vaccination, and protection lasted at least 12 months against RHDV2, highly virulent RHDV2, and classical RHDV strains [15].

Vaccine Efficacy Considerations

• Strain coverage: Vaccines should protect against both RHDV2 and classical RHDV strains. The recombinant vaccine studied in 2026 showed protection against all tested strains [15].
• Adjuvant effects: The choice of adjuvant influences immune response. A 2024 study found that ractopamine administration in rabbits receiving inactivated RHD vaccine affected immunological parameters, with potential implications for vaccine efficacy [12].
• Maternal antibody interference: Kits from vaccinated does may have maternal antibodies that interfere with early vaccination. Consult the vaccine manufacturer for specific recommendations.

Record Keeping

Maintain vaccination records for each rabbit or group, including:

• Vaccine product name and lot number
• Date of administration
• Dose and route
• Rabbit identification (ear tag, tattoo, or cage number)
• Name of person administering the vaccine
• Any adverse reactions observed

Biosecurity Measures

Effective biosecurity is essential for preventing RHDV2 introduction and controlling outbreaks.

Facility Design and Management

• Location: Site rabbitries away from wild rabbit habitats and areas with known RHDV2 activity.
• Perimeter control: Fence the facility to exclude wild animals and domestic animals.
• Ventilation: Design ventilation systems to minimize airborne transmission between pens.
• Drainage: Ensure proper drainage to prevent standing water that attracts insects.

Quarantine Protocols

• New arrivals: Quarantine all new rabbits for a minimum of 14 days, preferably 30 days, in a separate facility.
• Isolation: House sick or exposed rabbits in a separate isolation area with dedicated equipment and personnel.
• Testing: Consider PCR testing of quarantined animals before introduction to the main herd.

Personnel Hygiene

• Footbaths: Place disinfectant footbaths at all entrances to rabbit housing areas. Use 10% bleach solution or 1% sodium hydroxide, changed daily.
• Hand washing: Require hand washing with soap and water before and after handling rabbits.
• Protective clothing: Provide dedicated coveralls, boots, and gloves for each housing area.
• Visitor policy: Restrict visitor access, require visitors to wear protective clothing and follow biosecurity protocols.

Equipment and Feed Management

• Dedicated equipment: Use separate equipment for each housing area, disinfect between uses.
• Feed storage: Store feed in rodent-proof containers, avoid contamination with wild animal feces.
• Water quality: Provide clean drinking water, disinfect water lines regularly.
• Disinfection: Clean and disinfect all equipment, cages, and surfaces with appropriate disinfectants. The virus is inactivated by 10% bleach, 1% sodium hydroxide, and 2% glutaraldehyde.

Insect and Rodent Control

• Fly control: Use screens on windows and doors, implement integrated pest management for flies.
• Mosquito control: Eliminate standing water, use approved larvicides.
• Rodent control: Seal entry points, use traps and bait stations, maintain clean feed storage areas.

Manure and Carcass Disposal

• Manure: Compost manure properly, avoid spreading on pastures where rabbits graze.
• Carcasses: Dispose of dead rabbits by incineration, rendering, or deep burial according to local regulations. Do not leave carcasses where scavengers can access them.

Outbreak Management

When RHDV2 is suspected or confirmed, immediate action is required to contain the outbreak and prevent spread.

Immediate Response Steps

1. Isolate suspect animals: Immediately separate any rabbits showing clinical signs from the rest of the herd.
2. Contact veterinarian: Notify your veterinarian immediately for clinical assessment and diagnostic testing.
3. Report to authorities: Report suspected cases to the state veterinarian or appropriate animal health authority. RHDV2 is a reportable disease in many jurisdictions.
4. Stop movement: Halt all movement of rabbits, equipment, and personnel between facilities.
5. Implement enhanced biosecurity: Increase disinfection frequency, restrict access to essential personnel only.

Confirmed Outbreak Procedures

• Quarantine: The affected facility should be placed under official quarantine. No rabbits should enter or leave the premises.
• Depopulation: In severe outbreaks, depopulation of affected and exposed rabbits may be necessary to eliminate the virus. This decision should be made in consultation with veterinary authorities.
• Cleaning and disinfection: Thoroughly clean and disinfect all surfaces, equipment, and housing. Allow adequate contact time for disinfectants.
• Sentinel animals: After cleaning, place sentinel rabbits in the facility to monitor for virus persistence before restocking.
• Restocking: Wait at least 30 days after cleaning and sentinel testing before introducing new rabbits.

Vaccination During Outbreaks

• Emergency vaccination: Vaccination of at-risk rabbits may be used as part of outbreak control. Consult with veterinary authorities on the appropriate strategy.
• Ring vaccination: Vaccinate rabbits in a buffer zone around the affected facility to create a barrier to spread.

Communication

• Notify neighbors: Inform nearby rabbit owners and veterinarians about the outbreak.
• Coordinate with authorities: Work closely with animal health officials to implement control measures.
• Public information: Provide accurate information to the public to prevent panic and misinformation.

Records and Measurements

Maintaining detailed records is essential for effective disease prevention and outbreak management.

Herd Health Records

• Mortality records: Daily record of deaths with cause (if known). Track mortality rates by age group and housing area.
• Morbidity records: Record sick rabbits, clinical signs, and treatments administered.
• Vaccination records: As described above, including product, date, dose, and rabbit identification.
• Movement records: Document all rabbit movements into and out of the facility, including source, destination, and date.

Biosecurity Monitoring

• Footbath logs: Record date and time of footbath solution changes.
• Visitor logs: Document all visitors, including name, date, purpose of visit, and biosecurity measures followed.
• Disinfection logs: Record cleaning and disinfection activities, including areas treated, products used, and personnel responsible.

Diagnostic Records

• Test results: File all laboratory reports, including PCR, ELISA, and histopathology results.
• Necropsy reports: Document findings from post-mortem examinations.
• Veterinary consultations: Record all communications with veterinarians, including recommendations and actions taken.

Environmental Monitoring

• Temperature and humidity: Record environmental conditions in rabbit housing areas.
• Insect and rodent activity: Document pest control measures and any observed pest activity.
• Water quality: Test water sources periodically for bacterial contamination.

Common Failure Patterns

Understanding common mistakes in RHDV2 prevention and management can help rabbit owners avoid costly errors.

Inadequate Biosecurity

• Failure to quarantine: Introducing new rabbits without adequate quarantine is a leading cause of RHDV2 introduction.
• Shared equipment: Using the same equipment between different groups of rabbits without disinfection.
• Poor footbath maintenance: Allowing footbaths to become diluted or contaminated, failing to change solution daily.
• Wildlife access: Allowing wild rabbits, rodents, or birds access to rabbit housing or feed storage areas.

Vaccination Errors

• Incorrect vaccine storage: Storing vaccines at improper temperatures, reducing efficacy.
• Incomplete vaccination schedule: Failing to administer booster doses as recommended.
• Vaccinating sick rabbits: Vaccinating animals that are already incubating the disease.
• Using expired vaccines: Administering vaccines past their expiration date.

Delayed Response

• Ignoring early signs: Dismissing lethargy or decreased appetite as minor issues.
• Delayed reporting: Waiting to report suspected cases to veterinary authorities.
• Inadequate isolation: Failing to isolate sick rabbits promptly and effectively.

Environmental Persistence

• Incomplete disinfection: Using disinfectants that are ineffective against caliciviruses.
• Insufficient contact time: Not allowing disinfectants adequate time to work.
• Recontamination: Cleaning and disinfecting but then reintroducing contaminated equipment or materials.

Welfare and Safety Context

RHDV2 causes significant suffering in affected rabbits, making prevention and rapid response essential for animal welfare.

Welfare Implications

• Pain and distress: Infected rabbits experience fever, respiratory distress, and neurological signs before death.
• High mortality: Mortality rates in naive populations can exceed 80%, causing significant loss of life.
• Stress of control measures: Quarantine, depopulation, and enhanced biosecurity can cause stress for both rabbits and owners.

Human Safety Considerations

• Zoonotic risk: RHDV2 does not infect humans. There is no human health risk from handling infected rabbits, though standard hygiene practices should be followed.
• Disinfectant safety: Use appropriate personal protective equipment when handling disinfectants. Follow manufacturer safety instructions.
• Carcass handling: Wear gloves and protective clothing when handling dead rabbits. Dispose of carcasses according to local regulations.

Regulatory Context

• Reportable disease: RHDV2 is a reportable disease in many countries. Failure to report suspected cases may result in legal penalties.
• Movement restrictions: Outbreaks may trigger official movement restrictions that affect rabbit transport and commerce.
• Vaccination regulations: Some countries have specific regulations regarding RHDV2 vaccine use. Consult local veterinary authorities.

Professional Escalation Criteria

Contact a veterinarian immediately if:

• One or more rabbits die suddenly without apparent cause
• Multiple rabbits show signs of lethargy, fever, or respiratory distress
• You observe hemorrhages from the nose, mouth, or rectum
• Neurological signs such as ataxia or seizures are present
• Mortality rates exceed normal levels for your facility

Contact the state veterinarian or animal health authority if:

• RHDV2 is confirmed by laboratory testing
• You suspect an outbreak based on clinical signs and history
• You need guidance on quarantine or depopulation procedures

Practical Decision Framework for RHDV2 Vaccination: Strain Matching, Timing, and Response Assessment

Selecting and implementing an effective vaccination program against Rabbit Hemorrhagic Disease Virus 2 requires more than following a generic schedule. Rabbit owners and veterinarians must make specific decisions about vaccine strain coverage, timing relative to exposure risk, and methods for verifying immune response. This section provides a structured decision framework based on current evidence, practical assessment steps, and troubleshooting approaches for common vaccination challenges.

Vaccine Strain Matching: Understanding Cross-Protection and Variant Emergence

The genetic diversity of RHDV2 strains circulating globally requires careful attention when selecting a vaccine product. RHDV2 emerged as a recombinant virus between a non-pathogenic lagovirus (GI.3P) and a pathogenic GI.2 strain, and recombination continues to generate new variants [13]. A 2025 study identified a new RHDV2 variant in China with a mortality rate of 70-80% in domestic rabbits, where the nonstructural portion of the genome clustered with GI.1a variants while the capsid gene shared 97.9% nucleotide identity with North American GI.2 strains [13]. This finding demonstrates that recombination between different RHDV lineages can produce viruses that evade existing immunity.

When evaluating vaccine options, consider the following strain-related factors:

• Geographic relevance: Vaccines should be based on strains circulating in your region or closely related variants. A 2024 review of global detections from 2010 to 2023 documented RHDV2 in multiple countries across Europe, North America, Africa, Asia, and Australia, with varying strain distributions [10].

• Cross-protection evidence: Recombinant VP60 vaccines have demonstrated protection against multiple RHDV2 strains. A 2026 study showed that a VLP-based vaccine based on the Chinese YC05 strain protected rabbits against challenge with different clinical RHDV2 strains for at least 180 days [14]. Another 2026 study of a commercial recombinant vaccine found protection against RHDV2, highly virulent RHDV2, and classical RHDV strains for approximately 12 months [15].

• Recombinant risk monitoring: The potential for recombination between RHDV2 and classical RHDV has been documented. A 2020-2024 study in China detected RHDV2 in 86 of 205 clinical samples, with no classical RHDV detected, but recombination analysis indicated a potential risk of recombination between the two genotypes [14]. This underscores the importance of using vaccines that provide coverage against both genotypes when available.

Decision Framework for Vaccination Timing and Frequency

The optimal vaccination schedule depends on several farm-specific factors. Use the following decision matrix to determine appropriate timing for your operation.

Factor 1: Outbreak History and Regional Risk Level

Factor 2: Herd Demographics and Production Type

• Commercial meat or breeding operations: Vaccinate all animals, with particular attention to breeding does to provide maternal antibody transfer to kits. A 2024 study found that ractopamine administration in rabbits receiving inactivated RHD vaccine affected immunological parameters, including significant decreases in lymphocytes and serum globulin levels [12]. If using growth-promoting substances, consult with a veterinarian about potential impacts on vaccine response.

• Show or exhibition rabbits: Vaccinate at least 3-4 weeks before any event. Maintain documentation of vaccination dates and product lot numbers for event organizers.

• Pet rabbits: Vaccinate regardless of housing type. Indoor rabbits can be exposed through fomites, insects, or contaminated feed. A 2023 study on rabbit owners willingness to engage in disease prevention behaviors found that understanding of transmission routes influenced prevention practices [19].

Factor 3: Age at First Vaccination

The appropriate age for initial vaccination depends on maternal antibody levels and vaccine product specifications:

• Kits from unvaccinated does: Can be vaccinated as early as 4 weeks of age, as there is no maternal antibody interference.

• Kits from vaccinated does: Maternal antibodies may interfere with early vaccination. Consult the vaccine manufacturer for specific recommendations. In general, delaying first vaccination until 6-8 weeks of age may improve response, but this must be balanced against the risk of early exposure.

• Adult rabbits with unknown vaccination history: Administer initial dose immediately, followed by a booster 3-4 weeks later.

Practical Assessment Steps for Vaccine Response Verification

Verifying that vaccination has produced an adequate immune response is essential for confirming protection. Use the following assessment protocol.

Step 1: Pre-Vaccination Baseline Assessment

Before initiating a vaccination program, collect baseline data:

• Record current mortality rates by age group for the previous 6-12 months
• Document any previous RHDV2 exposure or vaccination history
• Note any concurrent health issues or treatments that might affect immune response
• Collect serum samples from a representative sample of rabbits (5-10% of herd, minimum 10 animals) for antibody testing if resources permit

Step 2: Post-Vaccination Monitoring Schedule

Step 3: Antibody Testing Interpretation

If using ELISA or hemagglutination inhibition testing to verify vaccine response:

• Positive response: Antibody levels significantly above pre-vaccination baseline, typically with hemagglutination inhibition titers of 1:25 or higher as demonstrated in VLP vaccine studies [14]

• Inadequate response: Antibody levels similar to pre-vaccination baseline or below protective threshold. Consider revaccination with a different product or adjuvant system.

• Interpretation limitations: Antibody levels do not always correlate perfectly with protection, as cellular immune responses also contribute. A 2019 study characterized both humoral and cellular immune responses induced by a recombinant baculovirus vaccine [17].

Records and Measurements for Vaccination Program Management

Maintain the following records to track vaccination effectiveness and identify problems early.

Vaccination Batch Record Template

Herd Immunity Monitoring Log

Vaccine Storage and Handling Log

Common Failure Patterns in Vaccination Programs

Understanding why vaccination programs fail helps rabbit owners take corrective action quickly.

Pattern 1: Vaccine Storage and Handling Errors

• Temperature abuse: Vaccines stored above 8°C or frozen lose potency. Record storage temperatures daily. If temperature excursions occur, consult the manufacturer before using the vaccine.

• Expired product: Using vaccines past their expiration date provides no guarantee of protection. Check expiration dates before each use.

• Improper reconstitution: Some vaccines require mixing before use. Follow manufacturer instructions exactly. Use the entire vial within the specified time after reconstitution.

Pattern 2: Timing and Schedule Failures

• Delayed booster: Extending the interval between initial and booster doses beyond 4 weeks may result in inadequate immunity. If the booster is delayed, restart the series.

• Early vaccination in kits with maternal antibodies: Vaccinating kits before maternal antibodies have waned can neutralize the vaccine. If kits from vaccinated does are vaccinated too early, consider revaccination at 8-10 weeks of age.

• Vaccinating during incubation period: Rabbits already exposed to RHDV2 before vaccination may develop disease despite vaccination. This is not a vaccine failure but a timing issue.

Pattern 3: Incomplete Population Coverage

• Missed individuals: Failing to vaccinate all rabbits in a facility leaves a susceptible population that can amplify virus if introduced. Maintain a vaccination roster and check it monthly.

• New arrivals: Introducing unvaccinated rabbits into a vaccinated herd creates a vulnerable subgroup. Quarantine and vaccinate all new arrivals before introduction.

• Young kits: Kits below vaccination age are susceptible. Ensure they are housed separately from potentially exposed rabbits and that their mothers are vaccinated to provide passive immunity.

Pattern 4: Concurrent Immunosuppression

• Stress: Overcrowding, poor nutrition, transport, or concurrent disease can suppress immune response to vaccination. Address stress factors before or simultaneously with vaccination.

• Medications: Some drugs may interfere with vaccine response. A 2024 study found that ractopamine, a beta-adrenergic agonist, affected immunological parameters in rabbits receiving inactivated RHD vaccine, including decreased lymphocytes and serum globulin levels [12]. Consult a veterinarian about potential interactions between medications and vaccine response.

• Parasite burden: Heavy internal or external parasite loads can divert immune resources. Treat significant parasite infestations before vaccination.

Troubleshooting Guide for Suspected Vaccine Failure

When RHDV2 occurs in a vaccinated population, use this systematic approach to identify the cause.

Step 1: Confirm the Diagnosis

• Submit samples from affected rabbits for PCR testing to confirm RHDV2 and rule out other causes of acute death
• If possible, have the virus sequenced to determine if it is a variant not covered by the vaccine
• A 2025 study identified a new recombinant RHDV2 variant in China that caused 70-80% mortality despite the existence of vaccines based on earlier strains [13]

Step 2: Review Vaccination Records

• Check that the correct vaccine product was used and that it was within its expiration date
• Verify that storage temperatures were maintained within the recommended range
• Confirm that the correct dose and route of administration were used
• Check that the full vaccination series (initial dose plus booster) was completed

Step 3: Assess Herd Immunity

• Calculate the percentage of rabbits that received the complete vaccination series
• If coverage is below 80%, unvaccinated animals may be amplifying virus and exposing vaccinated animals to high challenge doses
• Test a sample of vaccinated rabbits for antibody levels to verify immune response

Step 4: Evaluate Challenge Level

• Determine the likely source and intensity of virus exposure
• High-dose exposure through direct contact with infected rabbits may overwhelm vaccine protection
• Consider whether biosecurity failures allowed sustained virus introduction

Step 5: Consult with Veterinary Professionals

• Contact the vaccine manufacturer for technical support
• Report suspected vaccine failure to veterinary authorities
• Consider switching to a different vaccine product or adjuvant system
• A 2024 study evaluated the comparative effect of aluminum hydroxide gel and Montanide ISA 70 adjuvants in locally prepared RHDV2 vaccines, finding that adjuvant choice affects vaccine potency and protection [18]

Professional Escalation Criteria for Vaccination Program Issues

Contact a veterinarian immediately if:

• RHDV2 is confirmed in a vaccinated population
• Post-vaccination antibody testing shows inadequate response in more than 20% of tested animals
• Adverse reactions to vaccination occur in more than 1% of vaccinated rabbits
• You need guidance on selecting a vaccine product for a specific strain situation

Contact the vaccine manufacturer or veterinary authorities if:

• You suspect a vaccine lot is defective (e.g., multiple rabbits show no response to the same lot)
• You need information about strain coverage for a specific product
• You require assistance with vaccine storage or handling issues

Welfare and Safety Context for Vaccination Decisions

Vaccination decisions have direct welfare implications for rabbits and safety considerations for handlers.

Welfare Benefits of Effective Vaccination

• Prevention of severe disease and death from RHDV2
• Reduced need for depopulation during outbreaks
• Lower stress from disease and control measures
• Protection of young rabbits that are susceptible to RHDV2

Welfare Risks of Vaccination Errors

• Pain or discomfort from improperly administered vaccines
• Disease in vaccinated rabbits due to vaccine failure
• Stress from repeated handling for revaccination if initial schedule was incorrect

Human Safety Considerations

• Use appropriate restraint techniques when vaccinating rabbits to prevent injury to both handler and animal
• Follow needle safety protocols to prevent needlestick injuries
• Dispose of used needles and syringes in approved sharps containers
• Wash hands after handling vaccines and rabbits

Regulatory Compliance

• Maintain vaccination records as required by local regulations
• Report adverse reactions to vaccine manufacturers and regulatory authorities as required
• Follow movement restrictions related to vaccination status during outbreaks
• Some countries have specific regulations regarding RHDV2 vaccine use, including which products are licensed and whether vaccination is mandatory in certain situations

Frequently Asked Questions

What is the difference between RHDV and RHDV2?

RHDV (classical RHDV, GI.1) emerged in the 1980s and primarily affected adult rabbits, with young rabbits being resistant. RHDV2 (GI.2) emerged in 2010 and affects rabbits of all ages, including young kits. RHDV2 also infects a broader range of species, including hares. The two viruses are genetically distinct, and vaccines must be effective against RHDV2 to provide protection [10].

How long does RHDV2 survive in the environment?

RHDV2 is extremely stable and can survive for months in the environment under favorable conditions. The virus persists in contaminated feed, bedding, soil, and on surfaces. It is resistant to freezing and many common disinfectants. Effective disinfection requires 10% bleach, 1% sodium hydroxide, or 2% glutaraldehyde with adequate contact time.

Can my rabbit get RHDV2 if it is kept indoors?

Indoor rabbits have a lower risk of exposure but are not immune. The virus can be brought indoors on clothing, shoes, or equipment. Insects can enter homes and transmit the virus. Contaminated hay or feed can introduce the virus. Vaccination is recommended for all rabbits, regardless of housing.

How effective are RHDV2 vaccines?

Recombinant VP60 vaccines have shown strong efficacy in multiple studies. A 2024 study found that a baculovirus recombinant vaccine provided durable immunity [6]. A 2026 study demonstrated that a VLP-based vaccine protected rabbits for at least 180 days against different RHDV2 strains [14]. Another 2026 study showed that a commercial recombinant vaccine protected against RHDV2, highly virulent RHDV2, and classical RHDV strains for at least 12 months [15].

Can vaccinated rabbits still get RHDV2?

Vaccination significantly reduces the risk of disease but may not provide 100% protection in all cases. Factors affecting vaccine efficacy include proper storage and administration, timing of vaccination relative to exposure, and the immune status of the rabbit. Vaccinated rabbits that become infected may have milder disease and lower viral shedding.

How is RHDV2 diagnosed?

Diagnosis requires laboratory testing. PCR testing of liver, spleen, or blood is the most sensitive method. ELISA can detect antibodies in serum. Histopathology of liver tissue shows characteristic acute hepatic necrosis. Veterinarians should collect appropriate samples and submit them to a diagnostic laboratory.

What should I do if I suspect RHDV2 in my rabbits?

Immediately isolate any sick rabbits and contact your veterinarian. Do not move rabbits or equipment between facilities. Report suspected cases to the state veterinarian or animal health authority. Implement enhanced biosecurity measures, including footbaths and restricted access. Follow your veterinarian guidance on diagnostic testing and control measures.

Can wild rabbits transmit RHDV2 to domestic rabbits?

Yes, wild lagomorphs can serve as reservoirs for RHDV2 and transmit the virus to domestic rabbits. The 2020 outbreak in the western United States demonstrated how the virus can spread through wild populations and affect domestic rabbits [7]. Preventing contact between domestic and wild rabbits is an essential biosecurity measure.

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References and Further Reading

• www.merckvetmanual.com
• www.avma.org
• www.aemv.org
• Merck Veterinary Manual. Merck Veterinary Manual.
• Animal Health and Welfare. World Organisation for Animal Health.
• Vaccination against Rabbit Hemorrhagic Disease Virus 2 (RHDV2) Using a Baculovirus Recombinant Vaccine Provides Durable Immunity in Rabbits.. Viruses, 2024.
• Detections of Rabbit Hemorrhagic Disease Virus 2 (RHDV2) Following the 2020 Outbreak in Wild Lagomorphs across the Western United States.. Viruses, 2024.
• Early pathogenesis in rabbit hemorrhagic disease virus 2.. Microbial pathogenesis, 2022.
• Diagnosis of a Rabbit Hemorrhagic Disease Virus 2 (RHDV2) and the Humoral Immune Protection Effect of VP60 Vaccine.. Current issues in molecular biology, 2023.
• Rabbit hemorrhagic disease virus 2, 2010-2023: a review of global detections and affected species.. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 2024.
• Rabbit Haemorrhagic Disease Virus 2 (RHDV2, GI.2) in Ireland Focusing on Wild Irish Hares (Lepus timidus hibernicus): An Overview of the First Outbreaks and Contextual Review.. Pathogens (Basel, Switzerland), 2022.
• Immunological effects of ractopamine in rabbits receiving the viral inactivated rabbit hemorrhagic disease vaccine. Open Veterinary Journal, 2024.
• Detection of a New Recombinant Rabbit Hemorrhagic Disease Virus 2 in China and Development of Virus-like Particle-Based Vaccine. Viruses, 2025.
• Molecular characterization of rabbit hemorrhagic disease virus type 2 and long-lasting protection conferred by a VLP-based vaccine. BMC Veterinary Research, 2026.
• Protection Against Rabbit Hemorrhagic Disease Virus Strains: Efficacy of a New Commercial Recombinant RHDV2 Capsid Protein VP60 Vaccine. Vaccines, 2026.
• Also Belgian rabbits are affected by the rabbit hemorrhagic disease type 2 virus. Vlaams Diergeneeskundig Tijdschrift, 2016.
• Characterization of protective humoral and cellular immune responses against RHDV2 induced by a new vaccine based on recombinant baculovirus. Vaccine, 2019.
• Evaluation of comparative effect between aluminum hydroxide gel and montanide (ISA 70) in potency and protection of locally prepared rabbit hemorrhagic disease virus 2 (RHDV2) vaccines in rabbits. BMC Veterinary Research, 2024.
• Understanding rabbit owners’ willingness to engage in disease prevention behaviors. Preventive Veterinary Medicine, 2023.

This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.