Myxomatosis

Myxomatosis is a viral disease caused by the myxoma virus that is devastating to domestic and wild European rabbits. The disease was actually developed deliberately as a biological control agent to reduce wild rabbit populations in Australia in the 1950s and was later introduced to Europe for the same purpose. It worked horribly well. The virus causes severe swelling, discharge, and systemic illness that is fatal in the vast majority of infected domestic rabbits. If there is one disease that every rabbit owner should know about even if they hope never to encounter it, this is the one.

The geographic distribution of myxomatosis varies significantly. It is endemic in wild rabbit populations across Europe, the United Kingdom, and Australia, where it circulates continuously and poses a constant threat to domestic rabbits. In the United States, myxomatosis is much less common but not absent. Cases have been documented in the western states, particularly California and Oregon, where the virus exists in wild brush rabbit and jackrabbit populations. Wherever wild rabbits carry the virus, domestic rabbits in the area are at risk, especially during warm months when insect vectors are most active.

The mortality rate for myxomatosis in unvaccinated domestic rabbits is staggeringly high, often cited at ninety-six percent or above. Rabbits that have never been exposed to the virus have essentially no immune defense against it, and the disease progresses rapidly from initial symptoms to death, typically within ten to fourteen days. Even with intensive veterinary care, survival rates are extremely low for the classic form of the disease. There is a less virulent form that produces a milder illness in some cases, but counting on encountering the mild form is not a strategy.

What makes myxomatosis particularly concerning for rabbit owners is that the primary transmission route is through biting insects, which means your rabbit does not need to have direct contact with an infected rabbit to catch it. Mosquitoes, fleas, and other blood-sucking insects carry the virus from infected wild rabbits to domestic ones, sometimes over considerable distances. A rabbit that lives entirely indoors is at lower risk but not zero risk, because mosquitoes get into houses. Outdoor rabbits and those in areas with large wild rabbit populations face the highest danger.

This article covers how the virus spreads, what symptoms look like, what treatment options exist, and critically how to protect your rabbit through prevention measures and vaccination where it is available. Myxomatosis is a disease where prevention is everything because treatment options once infection occurs are extremely limited.

The myxoma virus is a poxvirus that specifically targets rabbits of the genus Oryctolagus, which includes all domestic pet rabbits and European wild rabbits. The virus replicates in the skin and lymph nodes, causing the characteristic swelling and immune suppression that makes the disease so lethal. It is remarkably stable in the environment and can survive on surfaces, in insect mouthparts, and on contaminated objects for extended periods, which contributes to its ability to spread.

The primary transmission route is through biting insects, particularly mosquitoes and rabbit fleas. When a mosquito feeds on an infected wild rabbit and then bites a domestic rabbit, it transfers the virus directly into the bloodstream. Rabbit fleas are especially efficient vectors because they stay on or near rabbits and move between individuals. In areas where wild rabbits carry the virus, every biting insect that could travel between wild and domestic rabbit populations represents a potential transmission event. This insect-mediated spread is why outbreaks tend to peak during warm weather months when mosquito and flea populations are highest.

Direct contact with infected rabbits or contaminated materials is the other transmission route. The virus is present in the discharge from infected rabbits' eyes, nose, and skin lesions, and any rabbit that contacts these fluids can become infected. Contaminated bedding, food dishes, cage materials, or even clothing and hands of humans who have handled infected rabbits can carry the virus to new hosts. This is why quarantine and hygiene practices are critical in multi-rabbit households or rescue situations where new rabbits are brought in.

Geographic location is the most significant risk factor. Rabbits living in areas where myxomatosis is endemic in the wild population face ongoing exposure risk. In the UK and Europe, the risk is year-round with peaks in late summer and autumn. In the western United States, risk exists but is lower and more localized. Rabbits living in rural areas near wild rabbit habitat are at higher risk than urban rabbits, though urban rabbits are not immune to mosquito-borne transmission.

Outdoor housing dramatically increases risk compared to indoor housing because outdoor rabbits have constant exposure to insect vectors. A rabbit in a hutch or outdoor enclosure has no protection from mosquitoes unless the enclosure is completely screened with fine mesh. Even covered outdoor runs leave gaps that insects can exploit. Indoor rabbits have significantly lower risk but are not completely safe during mosquito season when insects enter homes through open doors and windows. Vaccination status is the ultimate risk modifier in countries where the vaccine is available, essentially dividing rabbits into protected and unprotected categories.

The classic form of myxomatosis begins with swelling and redness around the eyes, which is often the first sign an owner notices. Within a day or two of the initial eye changes, the swelling becomes more severe and the eyelids may swell shut entirely. Thick purulent discharge develops around the eyes and nose, giving the rabbit a dramatically altered appearance. The swelling progresses to affect the ears, lips, nose, and genital area, creating the puffy, distorted facial features that are characteristic of the disease.

As the disease progresses beyond the initial swelling phase, the rabbit develops multiple raised lumps or nodules across the body, particularly on the ears, face, and around the base of the tail. These myxomas are the skin tumors that give the disease its name, and they can range from small bumps to large masses. The skin between the nodules may become thickened and develop a leathery texture. Some rabbits develop extensive skin lesions that weep fluid and become prone to secondary bacterial infections.

Behavioral changes follow rapidly as the disease takes hold systemically. An infected rabbit becomes lethargic, withdrawn, and increasingly unresponsive to interaction. Appetite drops quickly as swelling around the mouth and nose makes eating and breathing difficult. Fever develops as the immune system attempts to fight the infection, though the virus suppresses immune function so effectively that the response is ultimately inadequate. The rabbit may sit hunched in one spot, showing no interest in food, water, or their surroundings.

The discharge and elimination changes that accompany myxomatosis reflect the systemic nature of the infection. Breathing may become labored and audible as nasal passages swell and fill with mucus. Genital swelling can interfere with urination. Droppings decrease as food intake drops, and secondary GI slowdown often develops alongside the primary viral infection. The combination of immune suppression, inability to eat and drink, and secondary infections creates a cascading organ failure that the vast majority of rabbits cannot survive.

In the peracute form of the disease, which is less common, rabbits can die within forty-eight hours of the first symptoms appearing, sometimes before the classic swelling even develops fully. These rabbits may simply be found dead or nearly dead with minimal external signs. The atypical or nodular form, which occurs with less virulent strains of the virus, progresses more slowly and may present primarily as skin lumps without the dramatic facial swelling. This form has a somewhat better survival rate but still requires immediate veterinary attention.

Veterinary diagnosis of myxomatosis is often based on clinical presentation because the combination of bilateral eye swelling, facial edema, skin nodules, and discharge in a rabbit is highly characteristic. Your vet will examine the rabbit thoroughly and ask about potential exposure history, geographic location, outdoor access, and vaccination status. In areas where myxomatosis is common, experienced rabbit vets can often make a clinical diagnosis based on appearance alone, but laboratory confirmation through virus isolation or PCR testing of skin lesion samples may be pursued to confirm.

Blood work in myxomatosis cases typically shows evidence of immune suppression and may reveal secondary bacterial infections that have taken advantage of the weakened immune system. However, the diagnostic value of blood work is limited because by the time classic symptoms are present, the diagnosis is usually apparent from the physical exam. The primary value of additional testing is in atypical cases where the presentation is not classic, or in areas where myxomatosis is uncommon and needs to be differentiated from other conditions that cause facial swelling or skin lesions.

Treatment options for myxomatosis are extremely limited, and this is the difficult reality that rabbit owners need to understand. There is no antiviral medication that targets the myxoma virus. Treatment is entirely supportive, meaning the vet can address symptoms and secondary complications while the rabbit's immune system attempts to fight off the virus on its own. Supportive care includes fluid therapy to prevent dehydration, syringe feeding for rabbits that cannot eat, antibiotics to manage secondary bacterial infections, anti-inflammatory medications to reduce swelling, and eye ointments to protect the corneas when lids are swollen shut.

The conversation about euthanasia is one that comes up frequently and legitimately with myxomatosis cases. Given the extremely high mortality rate and the suffering involved in the disease course, many veterinarians will discuss humane euthanasia as a compassionate option, particularly when the classic severe form is diagnosed. This is not giving up on your rabbit. It is acknowledging that the disease causes significant suffering and that the odds of survival are very low even with intensive care. Each case is individual, and your vet can help you make the decision that is right for your rabbit's specific situation.

For rabbits where treatment is attempted, hospitalization is usually necessary for intensive supportive care. The rabbit needs round-the-clock monitoring, regular fluid administration, syringe feeding, wound care for skin lesions, and pain management. Even with all of this support, the survival rate for classic myxomatosis remains very low. Rabbits that do survive often have a prolonged recovery period and may have lasting effects including scarring and chronic eye problems.

Vaccination is the one genuinely effective medical intervention, but it is preventive rather than curative and is only available in certain countries. In the UK and Europe, the Nobivac Myxo-RHD Plus vaccine provides protection against both myxomatosis and rabbit hemorrhagic disease. The vaccine is given annually and is considered highly effective. In the United States, this vaccine is not currently licensed, which leaves American rabbit owners dependent on prevention through insect control and housing management rather than immunization.

Prevention is the cornerstone of dealing with myxomatosis because treatment options after infection are so limited. If you are in a country where the vaccine is available, get your rabbit vaccinated. This is the single most effective protective measure and should be maintained with annual boosters as recommended by your vet. If you are in the United States or another country where the vaccine is not available, prevention relies entirely on reducing your rabbit's exposure to the virus through insect control and housing management.

Insect control is critical for all rabbit owners in areas where myxomatosis exists. Use fine mesh screening on any outdoor enclosure to keep mosquitoes and flies out. Eliminate standing water near your rabbit's living area because mosquitoes breed in even small amounts of stagnant water. Use rabbit-safe flea prevention as recommended by your vet, particularly during warm months. Insect repellent products designed for other animals may be toxic to rabbits, so never apply anything without veterinary guidance. Keeping your rabbit indoors during peak mosquito activity times, particularly dawn and dusk, reduces exposure significantly.

If your rabbit is diagnosed with myxomatosis, home care under veterinary guidance involves keeping them warm, comfortable, and hydrated while managing symptoms. Gently clean discharge from the eyes and nose with warm damp cotton pads several times daily. Administer all prescribed medications on schedule, including antibiotics, pain relief, and eye treatments. Syringe feed Critical Care or a similar product if the rabbit cannot eat on its own. Keep the living area scrupulously clean and change bedding frequently to reduce secondary infection risk.

Ongoing monitoring if you live in an area where myxomatosis is present means staying aware of reported cases in your region, maintaining insect prevention measures consistently rather than only when you remember, and keeping your rabbit's living environment as insect-proof as practical. During outbreaks, consider keeping outdoor rabbits indoors temporarily until the risk subsides. If you bring a new rabbit into your household, quarantine them for at least fourteen days before allowing contact with your existing rabbits, particularly if you do not know their full health history.

The long-term reality for rabbit owners in endemic areas is that myxomatosis is a threat that requires consistent attention rather than a one-time fix. Vaccination where available provides strong protection and should be maintained without lapses. Where vaccination is not available, the combination of indoor housing, insect screening, flea prevention, and awareness of local disease activity provides the best available defense. Neither approach eliminates risk completely, but both reduce it substantially.

Seek immediate emergency veterinary care if your rabbit develops swelling around the eyes that appears suddenly, particularly if both eyes are affected. Any combination of eye swelling, nasal discharge, facial puffiness, or unexplained skin lumps in a rabbit warrants urgent evaluation, especially during mosquito season or in areas where myxomatosis has been reported. Early intervention gives the best possible chance at survival, limited as that chance may be, and also allows for prompt diagnosis that protects other rabbits in your household through quarantine measures.

Do not wait to see if symptoms resolve on their own. Myxomatosis progresses rapidly, and the window for meaningful supportive care is narrow. A rabbit that looks mildly unwell in the morning can be critically ill by evening. If your rabbit has outdoor access or lives in an area with wild rabbit populations and develops any of the signs described in this article, treat it as a potential myxomatosis case until your vet determines otherwise. The consequences of delayed treatment are severe, and the consequences of being cautious are minimal.

Your vet relationship is especially important for myxomatosis because of the emotional weight of the disease. A rabbit-savvy vet who knows you and your rabbit can have honest, compassionate conversations about prognosis and quality of life decisions that a stranger in an emergency clinic may not handle as well. Establish this relationship during healthy times so you have a trusted partner if crisis strikes. Discuss vaccination options and your specific risk level based on where you live and how your rabbit is housed.

If you have multiple rabbits and one is diagnosed with myxomatosis, contact your vet about the others immediately even if they appear healthy. Your vet may recommend emergency vaccination where available, enhanced insect prevention, separation from the infected rabbit, and close monitoring for early signs in housemates. The incubation period is typically five to fourteen days, so apparently healthy rabbits that were exposed may already be infected. Quick action gives you the best chance of protecting the rest of your rabbits.