Rabbit Hemorrhagic Disease

TL;DR. Rabbit Hemorrhagic Disease is a highly contagious and rapidly fatal viral infection that causes severe liver failure and internal bleeding in rabbits, making prevention and vaccination essential.

The rabbit hemorrhagic disease virus primarily targets the liver, causing rapid organ failure and systemic bleeding.

What is it?

Rabbit Hemorrhagic Disease (RHD) is a highly contagious, swift, and devastating viral disease that affects domestic and wild rabbits. Caused by the rabbit hemorrhagic disease virus (Lagovirus europaeus), which belongs to the Caliciviridae family, this pathogen is notorious for its extreme lethality and rapid progression. The virus primarily targets the liver, causing acute hepatic necrosis—a rapid and widespread destruction of liver cells. Because the liver is responsible for producing essential blood-clotting factors, this sudden destruction triggers a catastrophic, systemic condition known as disseminated intravascular coagulation (DIC).

The pathogenesis of Lagovirus europaeus is characterized by its tropism for hepatocytes, the primary functional cells of the liver. Once the virus enters the host's body, it rapidly targets these cells, utilizing specific cellular receptors to gain entry. Inside the hepatocyte, the virus replicates at an extraordinary rate, disrupting normal cellular machinery and leading to cell lysis (bursting). This massive, simultaneous destruction of liver cells is termed acute hepatic necrosis.

The liver is the central organ responsible for synthesizing coagulation factors—proteins essential for blood clotting. When the liver is suddenly destroyed, the synthesis of these factors halts. Concurrently, the massive release of cellular debris and tissue factor from the dying hepatocytes into the bloodstream triggers an uncontrolled, systemic activation of the coagulation cascade. This condition, known as disseminated intravascular coagulation (DIC), represents a state of hematological chaos. In the initial phase of DIC, microthrombi (tiny blood clots) form extensively throughout the capillary beds of vital organs, including the lungs, kidneys, and heart. This widespread clotting restricts blood flow, leading to tissue ischemia (lack of oxygen) and subsequent multi-organ failure. In the secondary phase of DIC, the body's supply of platelets and clotting factors is entirely exhausted. Without these essential components, the blood loses its ability to clot, resulting in widespread, spontaneous hemorrhaging. This dual process of micro-clotting and subsequent catastrophic bleeding is what makes RHD so rapidly fatal.

For rabbit owners, RHD represents one of the most significant infectious disease threats. The virus is incredibly stable in the environment, resisting physical and chemical breakdown, which allows it to spread easily over large distances. Because the disease often presents as sudden death with no prior signs of illness, understanding the transmission, symptoms, and preventative measures is critical for every rabbit caretaker.

Causes & risk factors

The primary cause of this disease is the rabbit hemorrhagic disease virus (Lagovirus europaeus). There are two main viral types: RHDV1 (the classic strain) and RHDV2 (a highly virulent variant that emerged more recently). While RHDV1 historically affected only adult European rabbits (Oryctolagus cuniculus), RHDV2 has a much broader host range, infecting rabbits of all ages—including young kits under eleven days old—as well as various species of wild hares and jackrabbits.

First recognized in China in 1984, Rabbit Hemorrhagic Disease quickly spread across Asia, Europe, and eventually to other parts of the world, including Australia and North America. The emergence of the RHDV2 variant in Europe in 2010 marked a significant shift in the epidemiology of the disease. Unlike the original RHDV1 strain, which had a narrow host range and spared young rabbits, RHDV2 proved to be highly adaptable, infecting multiple lagomorph species and causing high mortality even in kits as young as a few days old.

The persistence of the virus in the environment is a major factor in its rapid spread. Lagovirus europaeus is a non-enveloped virus, meaning it lacks a lipid outer membrane. Non-enveloped viruses are notoriously stable and resistant to environmental degradation. RHD can survive exposure to temperatures as high as 50°C (122°F) for up to an hour, remains stable across a wide pH range (from 3.0 to 9.0), and can survive in a dry environment on organic matter or carcasses for several months. This environmental resilience means that a rabbit can contract the virus from a pasture or cage that was contaminated by an infected rabbit months prior.

The virus is shed in high quantities in all bodily secretions from infected rabbits, including saliva, nasal discharge, urine, feces, and blood. Transmission occurs through several pathways:

• Direct Contact: Healthy rabbits can contract the virus by coming into direct contact with an infected rabbit, its secretions, or a carcass.
• Fomites: The virus is exceptionally hardy and can survive on inanimate objects for long periods. Clothing, shoes, car tires, cages, bowls, bedding, and grooming tools can easily transport the virus from an infected area to a clean environment.
• Mechanical Vectors: Biting insects such as fleas and mosquitoes, as well as non-biting flies, birds, and rodents, can mechanically carry the virus on their bodies or ingest it from carcasses and subsequently deposit it on healthy rabbits or their food.
• Contaminated Food and Water: Foraged greens, hay, or water sources contaminated by wild rabbits can introduce the virus to domestic indoor rabbits.

There are no breed predispositions for Rabbit Hemorrhagic Disease. Every breed of domestic rabbit, from the smallest Netherland Dwarf to the largest Flemish Giant, is equally susceptible to the virus. Because the virus can be brought indoors on shoes or clothing, even strictly indoor rabbits are at high risk if biosecurity measures are not maintained.

Signs to watch for

The clinical signs of Rabbit Hemorrhagic Disease are categorized into three forms: peracute, acute, and subacute. The peracute form is the most common and is characterized by a complete lack of clinical signs prior to death.

• Sudden death (Cardinal): Rabbits are often found dead in their enclosures with no prior indication of illness. This is the hallmark of the peracute form, where death occurs within hours of infection.
• Lethargy (Common): In the acute form, rabbits become profoundly weak, depressed, and reluctant to move. They may sit in a hunched posture and show no interest in their surroundings.
• Anorexia (Common): A sudden, complete refusal to eat food or drink water is a key sign of systemic illness in rabbits.
• Fever (Common): Affected rabbits develop a high fever, often exceeding 40°C (104°F). This fever typically peaks shortly before the onset of terminal hemorrhaging.
• Epistaxis (Common): Bleeding from the nose, which may appear as a bloody, frothy nasal discharge, is a common terminal sign resulting from severe lung hemorrhage.
• Dyspnea (Occasional): Difficulty breathing, rapid respiration, or gasping for air occurs as the lungs fill with blood or as the body enters shock.
• Icterus (Occasional): Yellowing of the mucous membranes, eyes, and skin can occur in rabbits that survive the initial acute phase for a few days, reflecting severe liver failure.
• Neurological signs (Occasional): Some rabbits may exhibit coordination loss, paddling of the limbs, or head pressing shortly before death due to hepatic encephalopathy or brain hemorrhages.

Severe lethargy and a reluctance to move are common early signs of Rabbit Hemorrhagic Disease.

How vets diagnose it

Diagnosing Rabbit Hemorrhagic Disease in a living patient is difficult because the disease progresses so rapidly that clinical intervention is rarely possible. When a rabbit is brought to a clinic showing severe, non-specific signs like lethargy and fever, your vet will perform a rapid clinical assessment while maintaining strict isolation protocols to prevent contaminating the clinic.

The gold standard for confirming a diagnosis of RHD is Reverse Transcription Polymerase Chain Reaction (RT-PCR). This molecular test detects the specific genetic material (RNA) of the virus. Because the liver is the primary site of viral replication, liver tissue collected post-mortem is the ideal sample for RT-PCR. In live rabbits, RT-PCR can sometimes be performed on blood samples or deep nasal swabs, but a negative result does not completely rule out the disease if the sample was taken early in the course of infection.

Histopathology of the liver is another gold standard diagnostic tool. A veterinary pathologist will examine liver tissue sections under a microscope to identify characteristic pathological changes. These include widespread lytic necrosis of hepatocytes (liver cells), ballooning degeneration, and the presence of microthrombi (tiny blood clots) in the blood vessels, which are diagnostic of DIC.

Additionally, an Enzyme-Linked Immunosorbent Assay (ELISA) can be utilized to detect RHDV antigens in tissue homogenates or blood. This test is highly useful for rapid screening and surveillance in areas experiencing outbreaks.

Reverse Transcription Polymerase Chain Reaction (RT-PCR) is the gold standard method for diagnosing Rabbit Hemorrhagic Disease.

Treatment options

There are no specific curative antiviral treatments or drug therapies available for Rabbit Hemorrhagic Disease in the clinical record or standard veterinary medicine. Once a rabbit exhibits clinical signs of RHD, the disease is almost always fatal, and treatment options are limited to supportive care.

Because of the highly contagious nature of the virus, any suspected case must be strictly quarantined. Supportive care measures, if attempted, are aimed at maintaining comfort and hydration:

• Fluid Therapy: Subcutaneous or intravenous fluids may be administered to support cardiovascular function and combat shock, though this must be done with extreme care to avoid overloading compromised lungs.
• Nutritional Support: Syringe feeding with high-fiber recovery diets can be attempted if the rabbit is stable enough to swallow safely, ensuring the gastrointestinal tract does not halt completely.
• Pain Management and Gastrointestinal Support: Medications to manage pain and support gut motility may be administered, though they do not alter the course of the liver failure.

In the vast majority of cases, due to the extremely poor prognosis and the high risk of environmental contamination, veterinary professionals will recommend humane euthanasia. This prevents further suffering and helps contain the spread of this highly resilient virus to other susceptible rabbits.

Prognosis

The prognosis for Rabbit Hemorrhagic Disease is grave. In susceptible, unvaccinated populations, mortality rates typically exceed 70% to 90%. For rabbits that develop a fever, death almost always occurs within 12 to 36 hours.

In rare instances where a rabbit survives the acute phase of the infection, they face a long and challenging recovery. These survivors often suffer from chronic, irreversible liver damage, which can lead to lifelong health complications, including digestive issues, clotting disorders, and general metabolic instability. Furthermore, surviving rabbits can shed the virus in their feces and secretions for several weeks or even months, serving as a source of infection for other rabbits. Long-term prognosis data in this species is limited because the vast majority of affected individuals succumb to the acute disease.

Prevention

Because there is no cure for RHD, prevention through vaccination and strict biosecurity is the only effective way to protect your rabbit. Highly effective vaccines are available that provide robust protection against both RHDV1 and RHDV2 strains. Your veterinarian can recommend a vaccination protocol, which generally starts when the rabbit is a few weeks old, followed by regular annual booster injections.

Alongside vaccination, implementing strict biosecurity protocols is vital to minimize the risk of introducing the virus to your home:

• Indoor Housing: Keep your rabbits indoors to eliminate direct contact with wild rabbits and reduce exposure to insect vectors.
• Sanitation and Disinfection: The calicivirus is highly resistant to many common household cleaners. To disinfect cages, bowls, and equipment, use a disinfectant proven to kill caliciviruses, such as a 1:10 dilution of household bleach or specialized veterinary virucidal disinfectants containing potassium peroxymonosulfate. Allow adequate contact time as directed by the manufacturer.
• Hygiene Practices: Always wash your hands thoroughly with soap and water before and after handling your rabbits. Remove outdoor footwear before entering the area where your rabbits live.
• Insect Control: Use rabbit-safe insect control methods, such as window screens and veterinary-approved flea preventatives, to protect your pets from mechanical vectors like flies and fleas.
• Quarantine: Isolate any new rabbit entering your home in a separate room for a minimum of 14 to 30 days. Use dedicated equipment and wash your hands and change clothes between handling the quarantined rabbit and your resident rabbits.
• Safe Foraging: Avoid harvesting wild grass, weeds, or branches from outdoor areas where wild rabbits may have traveled.

When to call your vet

Rabbit Hemorrhagic Disease is a critical veterinary emergency. You must contact your veterinarian or an emergency veterinary clinic immediately if your rabbit exhibits any of the following red-flag symptoms:

• Sudden, profound lethargy or collapse
• Complete loss of appetite (anorexia) lasting more than 12 hours
• Bleeding from the nose, mouth, or any other body orifice
• Difficulty breathing, rapid breathing, or gasping
• A high fever or sudden, unexplained death of a companion rabbit

If you suspect your rabbit has been exposed to RHD or if a rabbit in your household dies suddenly, do not bring the rabbit or carcass into a veterinary clinic without calling ahead first. This allows the clinic staff to prepare isolation protocols and prevent the potential spread of the virus to other patients.

Sources

Because there are no specific textbook citations provided in the record, this article is based on standard-of-care veterinary knowledge and official guidelines from leading international veterinary health organizations.

• World Organisation for Animal Health (WOAH) Terrestrial Manual: Chapter on Rabbit Hemorrhagic Disease.
• American Veterinary Medical Association (AVMA) Resources on Rabbit Hemorrhagic Disease Virus (RHDV2).
• Association of Exotic Mammal Veterinarians (AEMV) Clinical Practice Guidelines.