VHD Vaccination

Viral hemorrhagic disease, known as VHD or RHD (rabbit hemorrhagic disease), is one of the deadliest threats facing domestic rabbits, and vaccination is currently the only reliable protection against it. The disease kills quickly, often within 24 to 72 hours, with mortality rates above ninety percent in unvaccinated rabbits. There is no cure once a rabbit is infected. That combination of speed, lethality, and lack of treatment makes vaccination not just recommended but genuinely essential for any rabbit whose owner wants to protect them.

There are two main strains to understand. The original strain, RHDV1, has been known since the 1980s and has well-established vaccines available in many countries. The newer strain, RHDV2, emerged in Europe around 2010 and reached North America around 2020, spreading through wild rabbit populations and into domestic herds. RHDV2 is particularly concerning because it can affect younger rabbits than the original strain, has a slightly longer incubation period that allows more time for spread before detection, and can infect some wild hare and cottontail species that RHDV1 did not affect.

Vaccine availability varies dramatically depending on where you live. In the United Kingdom and much of Europe, combination vaccines covering both VHD strains and myxomatosis have been standard veterinary practice for years. In Australia, VHD vaccines are available and commonly used. In the United States, the situation has been more complicated due to regulatory pathways that were not designed to respond quickly to emerging animal diseases. Emergency use authorizations have made vaccines available in affected states, but access remains inconsistent.

The importance of VHD vaccination cannot be overstated for rabbits in regions where the disease has been confirmed. Even indoor rabbits are at risk because the virus is extraordinarily hardy and can survive on surfaces, clothing, shoes, and in hay for extended periods. Insect vectors can carry the virus into homes. The idea that an indoor rabbit is automatically safe from VHD is one of the most dangerous misconceptions in rabbit care today.

This article covers the specific vaccines available, recommended vaccination schedules, what to expect during and after vaccination, and how to access vaccines in areas where availability is limited. Protecting your rabbit from VHD is one of the most important health decisions you will make as a rabbit owner.

VHD is caused by a calicivirus that targets the liver, causing acute hepatic necrosis - essentially rapid liver failure. The virus replicates explosively once it establishes infection, overwhelming the rabbit's system before the immune response can mount an effective defense. Death results from liver failure, disseminated intravascular coagulation (a catastrophic blood clotting disorder), or both. The speed of this process is what makes the disease so devastating and treatment so futile once infection takes hold.

Transmission happens through multiple routes, which is part of what makes VHD so difficult to control through biosecurity alone. Direct contact between infected and healthy rabbits is the most obvious pathway, but the virus also spreads through contaminated food, bedding, water, and surfaces. Insects including flies, fleas, and mosquitoes can carry the virus mechanically on their bodies. Perhaps most concerning for indoor rabbit owners, the virus can hitch a ride on human clothing, shoes, and hands after contact with contaminated environments.

The virus is remarkably resilient in the environment. It can survive for months on dry surfaces at room temperature and even longer in cooler conditions. Standard household cleaning products do not reliably kill it - you need specific disinfectants like sodium hypochlorite (bleach) at appropriate concentrations or potassium peroxymonosulfate-based products. This environmental persistence means that once VHD is present in an area, the risk lingers long after the last visible case.

Risk factors for exposure include living in a state or region with confirmed RHDV2 cases in wild or domestic populations, having outdoor access or outdoor exercise time, attending rabbit shows or events, receiving hay from local sources where wild rabbits may graze, and living in proximity to wild rabbit populations. However, documented outbreaks in indoor-only rabbits with no obvious exposure pathway demonstrate that no environment provides complete protection without vaccination.

Unvaccinated rabbits of all ages, breeds, and living situations are susceptible to VHD. RHDV2 has been documented in rabbits as young as a few weeks old, unlike the original strain which primarily affected adults. There is no natural immunity, no breed resistance, and no husbandry practice that eliminates risk entirely. Vaccination is the one intervention that shifts the odds decisively in your rabbit's favor.

Seasonal factors can influence transmission rates but do not create safe periods. Insect activity peaks in warmer months, increasing vector-borne transmission, but the virus survives through winter on surfaces and in soil. Outbreaks have been documented in every season. Rabbit owners who only think about VHD during summer months are leaving their animals unprotected during periods when the virus is still circulating through other pathways.

The terrifying reality of VHD is that many rabbits die with little or no warning. The peracute form of the disease can kill within 12 to 36 hours of infection, and in some cases the first sign an owner notices is finding their rabbit dead with no prior indication of illness. This sudden death presentation is actually the most common outcome in unvaccinated rabbits exposed to the virus, which is why waiting for symptoms before seeking vaccination is a fundamentally flawed strategy.

When clinical signs do appear, they may include sudden loss of appetite, lethargy, and a high fever that the rabbit cannot regulate. The rabbit may seem dull, unresponsive, or reluctant to move. Some rabbits show signs of abdominal pain, pressing their belly to the ground or adopting a hunched posture. These early signs are non-specific and could indicate many different conditions, which makes them difficult to interpret as VHD specifically without the context of known local outbreaks.

As the disease progresses rapidly, bleeding disorders become apparent. Some rabbits develop bloody nasal discharge, blood in the urine, or bleeding from the gums. Others show bruising under the skin or bloody diarrhea. These hemorrhagic signs reflect the collapse of the blood clotting system that the virus triggers and represent a very late stage of disease where intervention is almost never successful.

Neurological signs including seizures, paddling movements, and sudden collapse can occur as the liver fails and toxins accumulate in the bloodstream. Respiratory distress from fluid accumulation in the lungs is another late-stage presentation. By the time any of these severe signs appear, the rabbit is in critical condition and survival is extremely unlikely regardless of treatment.

In the context of vaccination, the signs to watch for are much milder and temporary. After receiving a VHD vaccine, some rabbits show slight lethargy or reduced appetite for 12 to 24 hours. A small swelling at the injection site may develop and resolve within a few days. Serious adverse reactions to VHD vaccines are rare. Any reaction lasting more than 48 hours or involving difficulty breathing, significant swelling, or collapse should prompt an immediate vet call, but these events are uncommon.

If you live in a multi-rabbit household and one rabbit dies suddenly, watch the remaining rabbits closely and contact your vet immediately. The incubation period for VHD ranges from one to five days, so surviving rabbits who were exposed may already be infected without showing signs. Your vet can advise on emergency vaccination, isolation protocols, and environmental decontamination to protect those who may not yet be infected.

Diagnosis of VHD in a living rabbit is challenging because the disease progresses so rapidly that most diagnostic efforts happen post-mortem. If VHD is suspected in a living rabbit based on clinical signs and known exposure or local outbreak activity, your vet may submit blood samples for PCR testing, though results often come back after the rabbit has already died or recovered. Liver enzymes will typically be dramatically elevated, and blood clotting tests will show severe abnormalities.

Post-mortem diagnosis through necropsy and tissue testing is how most VHD cases are confirmed. If a rabbit dies suddenly and unexpectedly, especially if other rabbits in the area have died similarly, your vet should recommend submitting samples to a diagnostic laboratory. Confirming VHD cases is important not just for closure but for public health reporting that helps track the spread of the disease and alerts other rabbit owners in the area.

Treatment for active VHD infection is limited to supportive care, and honestly, outcomes are poor. Intravenous fluids, liver support medications, and aggressive nursing care may help a small percentage of rabbits survive, particularly those with the subacute form of RHDV2 which progresses slightly slower than the classic strain. However, rabbits who survive may suffer permanent liver damage and can shed virus for weeks, posing a risk to other unvaccinated rabbits.

Vaccination is the treatment in the preventive sense, and it is far more effective than any intervention after infection. Currently available vaccines include products specifically targeting RHDV2, and in some regions, combination vaccines covering both RHDV1 and RHDV2. In the US, vaccines produced under emergency use authorization have been the primary option, with regulatory status evolving as more data accumulates. Your rabbit-savvy vet will know which specific products are available in your area and which are appropriate for your rabbit.

The standard vaccination protocol involves an initial dose followed by a booster two to four weeks later, depending on the specific product, then annual revaccination. Some vets in high-risk areas recommend boosters every six months during active outbreak periods. Rabbits can typically be vaccinated starting at around four to ten weeks of age depending on the vaccine used, with the specific age determined by the product and your vet's assessment.

Cost for VHD vaccination is typically modest, ranging from twenty to sixty dollars per dose depending on location and the specific vaccine available. When weighed against a disease with over ninety percent mortality and no treatment, the value proposition is about as clear as it gets in veterinary medicine. If your vet offers VHD vaccination and your rabbit has not been vaccinated, there is no good medical reason to delay.

After vaccination, keep an eye on your rabbit for the rest of the day and through the next morning. Most rabbits show zero reaction. A few may seem a touch quieter than usual or eat slightly less for a meal or two. This is normal immune response and not cause for concern. If your rabbit stops eating entirely, shows significant swelling beyond a small bump at the injection site, or seems genuinely distressed, call your vet for guidance.

Keep your vaccination records organized and track when boosters are due. A simple note in your phone calendar works - set a reminder for two weeks before the annual booster is due so you have time to schedule the appointment. If you have multiple rabbits, keep a simple chart with each rabbit's name, vaccination dates, and next due dates. Letting boosters lapse means your rabbit's immunity may decline below protective levels.

Biosecurity measures at home complement vaccination but should not replace it. Change shoes before entering your rabbit's area if you have been outdoors in areas where wild rabbits live. Wash hands before handling your rabbit if you have been around other rabbits or at pet stores. Insect control through screens, fly paper, and flea prevention reduces vector transmission risk. Store hay in sealed containers and source it from reputable suppliers.

If you have multiple rabbits and one is unvaccinated due to age, health concerns, or recent acquisition, separate that rabbit from vaccinated animals until they can complete their vaccination series. New rabbits entering your household should be quarantined for at least fourteen days and ideally vaccinated before joining your existing group. This protects both the new rabbit and your current animals during the vulnerable period before immunity develops.

Stay informed about VHD activity in your area. State veterinarian offices, the USDA, and organizations like the House Rabbit Society publish updates on confirmed cases and outbreaks. Knowing whether the disease is active near you helps you make informed decisions about timing of vaccinations, level of biosecurity precautions, and whether to modify your rabbit's outdoor access or show participation.

If your rabbit is not yet vaccinated against VHD, schedule a vaccination appointment as soon as you can. Do not wait for a local outbreak to motivate you because by the time cases are confirmed in your area, the virus has already been circulating. Vaccination takes two to four weeks after the initial series to build full immunity, so starting before there is an obvious threat gives your rabbit the best protection.

If a rabbit in your household or community dies suddenly and unexpectedly, contact your vet immediately even if your surviving rabbits seem fine. Sudden death in a rabbit should always be investigated, and if VHD is suspected, your vet can advise on emergency biosecurity measures, testing, and whether emergency vaccination of exposed rabbits is appropriate. Some vets will administer vaccine to exposed but not yet symptomatic rabbits in hopes that immunity develops faster than infection progresses.

Seek a rabbit-savvy vet who carries VHD vaccine and stays current on outbreak tracking. Not every exotic vet has the vaccine in stock, and some may not be familiar with current recommendations. Call ahead and ask specifically whether they carry RHDV2 vaccine, what product they use, and what their recommended protocol is. If your local options do not carry it, ask for referrals to clinics that do - some owners drive an hour or more for vaccination, and that trip is worth making.

Do not let access barriers become an excuse for inaction. If you cannot find a local vet with VHD vaccine, contact your state veterinarian's office for information about where it is available. Reach out to local rabbit rescue organizations who often maintain lists of participating clinics. The inconvenience of accessing the vaccine is real but temporary, and it pales against the permanent consequence of losing a rabbit to a preventable disease.