Myxomatosis in Rabbits: Swollen Eyelids, Skin Lesions, and Emergency Signs

Myxomatosis is a serious viral disease caused by the myxoma virus, a member of the poxvirus family. It affects rabbits and can cause dramatic swelling around the eyes, ears, face, and genitals, along with skin nodules, discharge, fever, and breathing problems. In pet rabbits, this disease is considered an emergency because it can worsen quickly and has a high death rate.

Domestic rabbits are especially vulnerable when they are exposed to infected biting insects or infected rabbits. Wild rabbits may carry related virus strains with fewer signs, but pet rabbits can become critically ill. In the United States, cases have been reported most often in the western U.S., including California and Oregon, though risk depends on local wildlife and insect activity.

For pet parents, the most important point is this: swollen eyelids plus skin lesions in a rabbit should never be watched at home for a day or two. Rabbits hide illness well, and by the time swelling, discharge, or lethargy is obvious, they may already be dehydrated, painful, and at risk for secondary infections or pneumonia.

Myxomatosis is not known to infect people or typical household pets like dogs and cats, but it can spread between rabbits. If you suspect it, separate your rabbit from other rabbits right away and call your vet before transport so the clinic can prepare safe isolation steps.

Myxomatosis is caused by infection with the myxoma virus. The virus is spread most commonly by biting insects and external parasites, especially fleas and mosquitoes, and also mites and ticks. This is why outdoor rabbits and rabbits living in areas with wild rabbit populations are at higher risk.

Direct spread can also happen through contact with an infected rabbit's eye or nasal discharge. Less commonly, the virus may be carried on contaminated bedding, food bowls, water bottles, or other items in the environment. Some veterinary sources also note transmission through skin injuries caused by contaminated plant material such as thorns.

Risk is not equal everywhere. In the U.S., myxomatosis has been reported more often in the western states, and seasonal insect activity can increase exposure risk. Indoor rabbits are generally safer, but they are not completely risk-free if insects enter the home or if a new rabbit is introduced without quarantine.

Pet parents should also be careful with parasite products. Do not use dog or cat flea products on rabbits unless your vet specifically says they are safe for rabbits. Some common ingredients used in other species can be dangerous or even life-threatening for rabbits.

Your vet will start with a physical exam and a careful history, including recent outdoor time, insect exposure, contact with wild rabbits, and whether any new rabbits were added to the home. In many cases, the combination of swollen eyelids, facial edema, skin nodules, discharge, and fever creates a strong suspicion for myxomatosis.

Diagnosis often begins with clinical signs, but confirmation may require additional testing. Depending on the case, your vet may recommend bloodwork, cytology or tissue sampling from lesions, and laboratory testing such as PCR or other virus-specific tests on blood or tissue. These tests help distinguish myxomatosis from other causes of swelling, skin lesions, or respiratory disease.

Because rabbits with myxomatosis can also develop secondary bacterial infections, pneumonia, dehydration, and poor gut motility, your vet may assess hydration status, body temperature, oxygenation, and gastrointestinal function at the same visit. Imaging or additional monitoring may be needed if breathing is labored.

In some regions, suspected cases may need to be reported to animal health authorities. If your vet is concerned about myxomatosis, follow isolation instructions closely and avoid exposing other rabbits during transport, hospitalization, or home care.

Prevention centers on reducing exposure to the virus and the insects that spread it. The safest approach for most pet rabbits is indoor housing, especially in areas where myxomatosis has been reported or where wild rabbits are common. Window screens, mosquito barriers, and careful control of fleas and other parasites can lower risk further.

Avoid contact between your rabbit and wild rabbits, and quarantine any new rabbit before introductions. Wash hands, change clothing, and clean equipment if you have handled unfamiliar rabbits or visited places where rabbits are housed. Shared bowls, bedding, carriers, and grooming tools should be cleaned before use with another rabbit.

Talk with your vet about rabbit-safe parasite prevention. This matters because some products marketed for dogs or cats can be dangerous in rabbits. Your vet can help you choose options that fit your rabbit's health status, housing, and local insect pressure.

A myxomatosis vaccine is used in some parts of Europe and the UK, but it is not approved for rabbits in the United States as of March 2026. That means prevention in the U.S. depends mainly on housing, insect control, quarantine, and fast veterinary attention if any suspicious swelling or skin lesions appear.