Herpesvirus Infection in Rabbits: Rare but Important Viral Disease

Herpesvirus infection in rabbits is an uncommon viral disease. Merck notes that viruses are not major causes of clinical disease in rabbits in the United States, but herpesvirus infection has been recognized as one of the rare viral conditions reported in this species. Most pet parents will never encounter it, yet it still matters because the illness can be severe when it does occur.

The best-described naturally occurring form in domestic rabbits has been linked to leporid herpesvirus-4 (LHV-4), an alphaherpesvirus. Published case reports and pathology reviews describe rabbits with acute hemorrhagic pneumonia, dermatitis, conjunctivitis, splenic injury, and sudden death. In some outbreaks, rabbits housed outdoors or near wild rabbits and biting insects appeared to be at higher risk.

Because this infection is rare, it is often not the first thing your vet considers. More common rabbit problems like bacterial respiratory disease, trauma, reproductive disease, or rabbit hemorrhagic disease may look similar at first. That is why a rabbit with breathing trouble, bleeding from the nose, severe lethargy, or rapid decline needs timely veterinary care rather than watchful waiting.

Rabbit herpesvirus disease is caused by infection with a herpesvirus, most notably leporid herpesvirus-4 in the best-documented domestic rabbit cases. Pathology literature also notes that rabbits can be affected by several herpesviruses overall, but LHV-4 is the one most associated with acute systemic disease, pneumonia, dermatitis, and mortality in pet and commercial rabbits.

Exactly how infection spreads in every setting is not fully mapped out, which is one reason this disease remains important but poorly understood. Reported outbreaks suggest transmission may involve direct contact with infected rabbits, contaminated secretions, and possibly mechanical spread by biting insects in outdoor housing. Some outbreaks occurred where mosquitoes and biting flies were abundant and where wild or feral rabbits were nearby.

Stress, crowding, outdoor exposure, and close contact among rabbits may increase risk, especially in colony or rabbitry settings. One report also described perinatal losses in a breeding rabbit that had recovered from earlier infection, raising concern that reproductive effects may occur in some cases. Because the disease is rare, your vet will usually also consider more common causes of similar signs, including bacterial pneumonia, myxomatosis in endemic areas, and rabbit hemorrhagic disease.

Diagnosis starts with a careful history and physical exam. Your vet will ask about recent boarding, outdoor time, exposure to wild rabbits, insect exposure, new rabbits in the home, appetite changes, breathing changes, and any sudden deaths in nearby rabbits. Since herpesvirus infection is rare, the first step is often ruling out more common and more contagious rabbit diseases.

Testing may include bloodwork, chest radiographs, and sampling of nasal, eye, or skin lesions when present. If pneumonia is suspected, imaging can help show how severe the lung disease is. In some cases, your vet may recommend PCR or other specialized infectious disease testing through a veterinary diagnostic laboratory, although herpesvirus-specific testing in rabbits is not always readily available in general practice.

A confirmed diagnosis often depends on advanced pathology, especially in severe or fatal cases. Published reports describe diagnosis through virus isolation, electron microscopy, gene sequencing, histopathology, and identification of characteristic intranuclear viral inclusions in affected tissues. If a rabbit dies unexpectedly, necropsy can be very valuable, both for answers and for protecting other rabbits in the household.

Because rabbit herpesvirus infection is rare and not fully understood, prevention focuses on reducing infectious exposure overall. Keep pet rabbits away from wild rabbits and feral rabbits, avoid sharing bowls or supplies between unfamiliar rabbits, and quarantine any new rabbit before introductions. If you have multiple rabbits, separate any rabbit that develops respiratory signs, eye discharge, skin sores, or sudden lethargy until your vet advises otherwise.

Outdoor housing may increase exposure to insects and wildlife. If your rabbit spends time outside, use secure housing, reduce mosquito and biting fly exposure, and keep the area clean and dry. Good ventilation, low stress, and avoiding overcrowding also support general rabbit health and may reduce spread of infectious disease in group settings.

Routine veterinary care still matters, even for a rare disease. Your vet can help you sort out which vaccines, parasite prevention steps, and biosecurity measures make sense for your region. In the United States, more common viral threats such as rabbit hemorrhagic disease may be a bigger day-to-day concern than herpesvirus, so prevention plans should be tailored to your rabbit’s lifestyle and local risk.