Myxomatosis is a severe, highly contagious disease that primarily affects domestic and wild European rabbits (Oryctolagus cuniculus). Caused by a specific pathogen, this illness is often devastating to susceptible populations, resulting in high fatality rates. Historically, the virus was intentionally introduced in countries like Australia and Europe to control wild rabbit populations. It remains a significant threat to rabbit health globally, requiring vigilance from owners and veterinarians.
The Viral Agent and Transmission
The disease is caused by the Myxoma virus (MV), which belongs to the Poxvirus family, genus Leporipoxvirus. In its native hosts, such as the wild South American jungle rabbit, the virus causes only a localized, mild skin condition. When it infects the European rabbit species, however, the virus triggers a widespread, systemic, and often fatal illness.
Transmission occurs mainly through biological vectors, specifically biting insects. Mosquitoes and rabbit fleas are the most common carriers, transferring the virus mechanically when they feed on an infected animal and then immediately bite a healthy one. The virus can persist on the mouthparts of these arthropods, allowing for efficient spread.
Direct contact is another significant method of spread, particularly through secretions from the eyes, nose, and open lesions of an infected rabbit. Since the virus can survive outside a host, indirect transmission via contaminated objects, known as fomites, is possible. Items like cages, food dishes, or bedding can harbor the virus, making environmental disinfection important for outbreak control.
Recognizing the Clinical Signs
The incubation period typically ranges from eight to twenty-one days after exposure, though the strain’s severity influences this timeline. Initial signs often include a high fever, lethargy, and a sudden loss of appetite. These general symptoms rapidly progress to the characteristic physical manifestations of the disease.
The hallmark sign is the appearance of puffy, gelatinous swellings, known as myxomas. These fluid-filled swellings are most noticeable around the head, ears, and face, often giving the rabbit a “lion-head” appearance. Severe swelling of the eyelids often leads to temporary or permanent blindness, and a milky discharge from the eyes and nose is common.
Further myxomas develop around the lips, nostrils, and genitals, making eating, drinking, and breathing difficult. Because the virus severely suppresses the immune system, many rabbits succumb to secondary bacterial infections, such as pneumonia. Unvaccinated rabbits often experience a rapid decline in health, with death usually occurring within ten to fourteen days of the first clinical signs.
Disease Management and Prevention
There is no specific cure for Myxomatosis, making prevention the most effective strategy against the disease. Once a rabbit is infected, management focuses on intensive supportive care aimed at alleviating suffering and supporting the immune response. This care includes fluid therapy, pain management, and the use of antibiotics to treat or prevent secondary bacterial infections like pneumonia.
The prognosis for unvaccinated rabbits remains poor, and many veterinarians recommend humane euthanasia to prevent prolonged suffering. For rabbits that survive the initial phase—often those infected with less virulent strains or previously vaccinated—recovery can take several weeks, potentially leaving residual skin lesions.
Vaccination is the primary method of protection and is widely available and recommended in many regions outside of the United States. While vaccination may not prevent infection completely, it dramatically reduces the disease’s severity to a milder, localized form, significantly improving survival chances. Owners should also focus on strict vector control by using rabbit-safe flea preventatives and installing fine-mesh screens on outdoor hutches to prevent access by biting insects.