Rabbit Myxomatosis: Signs, Spread, and Prevention

Myxomatosis is a devastating viral disease of rabbits caused by a poxvirus, spreading through insect bites and direct contact — it is almost universally fatal in domestic rabbits without vaccination, and cases are rising in parts of North America where the virus has established itself. Recognizing the signs early and understanding prevention are critical for every rabbit owner.

Last reviewed: June 2026

What Is Myxomatosis and Where Does It Come From?

Myxomatosis is caused by the Myxoma virus, a member of the Poxviridae family. The virus evolved in South American cottontail rabbits (Sylvilagus species), in which it causes only mild localized skin lesions. It is catastrophically lethal in European domestic rabbits (Oryctolagus cuniculus) — the species of virtually all pet rabbits — producing mortality rates of 95–100% in naive (unvaccinated) populations.

The virus was deliberately introduced in several countries as a biological control for wild rabbit populations (most infamously in Australia in 1950 and in France in 1952, from where it spread through Europe). In the United States, myxomatosis is endemic in wild brush rabbits and Sylvilagus populations in California and coastal Oregon; cases in domestic rabbits are reported predominantly in the western US, though isolated cases from transported rabbits occur elsewhere. In the UK and much of Europe, myxomatosis is enzootic and a leading cause of rabbit death, making vaccination standard practice. In the US, no licensed vaccine is currently available, making prevention entirely dependent on mosquito, flea, and mite control.

As described in Quesenberry & Carpenter's Ferrets, Rabbits & Rodents: Clinical Medicine and Surgery, the Myxoma virus is highly species-specific and poses no risk to humans, dogs, cats, or other mammals — only lagomorphs (rabbits and hares) are susceptible.

How Myxomatosis Spreads

Understanding transmission is essential for prevention:

Insect vector transmission (most common):

• Mosquitoes — the primary vector in North America; a mosquito that fed on an infected wild rabbit carries virus on its mouthparts (mechanical transmission) and can inoculate a domestic rabbit immediately
• Fleas — particularly the rabbit flea (Spilopsyllus cuniculi), the primary vector in Europe; also cat fleas and dog fleas
• Biting flies, mites, and other biting arthropods — any blood-feeding insect can potentially carry the virus mechanically

Direct contact transmission:

• Contact with an infected rabbit (secretions, lesions, respiratory droplets)
• Contact with contaminated fomites (bedding, hutches, equipment from infected animals)
• Infected rabbit carcasses and their insects

Mosquitoes can carry the virus for up to several hours between hosts, meaning a domestic rabbit does not need to be in direct contact with wild rabbits — shared airspace near a screen, outdoor runs, or even transient mosquito entry indoors can be sufficient for infection. This reality makes insect prevention the most critical preventive tool for US rabbit owners.

Signs of Myxomatosis

The classic (acute) form progresses rapidly; a peracute form causes death before obvious signs develop:

Classic form — progression over 1–2 weeks:

Days 1–3 — prodromal signs:

• Puffy, swollen eyelids (blepharitis) — often the first noticeable change; the rabbit appears to have "sleepy eyes"
• Redness and discharge from the eyes (conjunctivitis)
• Mild lethargy and decreased appetite

Days 3–8 — characteristic stage:

• Progressive swelling of the eyelids, face, lips, ears, and genitalia — the face takes on a dramatically bloated appearance; the nose and lips swell grotesquely
• Mucopurulent (thick, yellow-green) discharge from the eyes and nose
• Characteristic skin nodules or swellings on the head, ears, and body — these are the "myxomas" (gelatinous subcutaneous swellings)
• Lethargy becomes profound; the rabbit often cannot see due to eye swelling
• High fever (40–41°C / 104–106°F)
• Loss of appetite progressing to complete anorexia

Days 8–14 — terminal phase:

• Secondary bacterial pneumonia — the rabbit develops severe respiratory distress
• Septicemia and systemic collapse
• Death

Peracute (hyperacute) form:

• Sudden death within 1–2 days, often before any external signs of myxomatosis are apparent; the rabbit is found dead
• More common in first-time exposures to highly virulent strains

Chronic or attenuated form (seen in partially immune animals or with some strains):

• Less severe nodular skin disease, less facial swelling; may survive weeks with intensive supportive care
• Seen more frequently in UK rabbits with some prior herd immunity; rare in naive US domestic populations

Any rabbit showing progressive eye swelling, facial puffiness, or skin nodules in a region where myxomatosis occurs should be considered a suspected case and isolated immediately from other rabbits (AEMV Pet Care Guides, 2024).

Myxomatosis vs. Other Rabbit Illnesses: Comparison

Feature	Myxomatosis	Rabbit Hemorrhagic Disease (RHDV2)	Pasteurellosis (snuffles)
Facial swelling	Severe, characteristic	No	Mild
Eye swelling/discharge	Severe, mucopurulent	Variable	Moderate
Skin nodules	Yes	No	No
Sudden death	Possible (peracute)	Common	Uncommon
Respiratory signs	Secondary (late)	Present	Common (nasal)
Transmission	Insect vectors / contact	Fomites / direct	Direct / contact
US vaccine available	No	USDA-conditional	No
Mortality unvaccinated	~95–100%	~70–100%	Low with treatment

Treatment

There is no specific antiviral treatment for myxomatosis. Care is entirely supportive, and prognosis is grave in unvaccinated domestic rabbits. Euthanasia is often the most humane option for severely affected rabbits, particularly those that have reached the facial swelling stage.

Supportive care for early or mild cases:

• Fluid therapy — subcutaneous or intravenous to maintain hydration
• Syringe feeding and assisted nutrition — anorexia rapidly leads to GI stasis and hepatic lipidosis in rabbits
• Antibiotics — to treat or prevent secondary bacterial infections (especially pneumonia); common choices include trimethoprim-sulfa, enrofloxacin, or penicillin G at rabbit-appropriate doses
• Eye lubricants and cleaning — gentle cleaning of eye discharge to maintain comfort
• Analgesics — meloxicam for pain and inflammation; dosing as described in Quesenberry & Carpenter's Ferrets, Rabbits & Rodents: Clinical Medicine and Surgery
• Isolation from all other rabbits — strict barrier nursing

Survival is possible in mild or attenuated cases with aggressive supportive care, but full recovery in naive domestic rabbits with the classic form is uncommon.

Prevention: Insect Control Is Everything in the US

Since no licensed vaccine exists in the US (unlike Europe, where live attenuated vaccines are available and widely used), prevention relies entirely on eliminating insect vector exposure:

• Screen all windows, doors, and ventilation openings — fine-mesh screens that exclude mosquitoes
• No outdoor access during dawn and dusk — peak mosquito activity periods
• Mosquito-safe outdoor runs — fully enclosed in fine mesh if outdoor time is allowed
• Flea and mite prevention — regular treatment with rabbit-safe products (selamectin, imidacloprid); never use products labeled for dogs without veterinary guidance, as many are toxic to rabbits
• No contact with wild rabbits or their carcasses
• Quarantine new rabbits — 3–4 weeks before introducing to established rabbit households

In the UK and Europe, annual vaccination with the licensed Nobivac Myxo-RHD Plus vaccine is the standard and most effective preventive measure, as described in the AEMV Pet Care Guides, 2024.

When to See a Vet

Call your vet today if:

• Your rabbit's eyes appear puffy, swollen, or producing discharge
• Your rabbit is less active than usual and eating less
• You notice any nodular swellings, lumps, or puffiness on the face, ears, or body
• You live in California, Oregon, or another area with known myxomatosis cases

Go to the ER immediately if:

• Your rabbit's face, nose, or genitals are dramatically swollen
• Your rabbit is gasping, breathing with its mouth open, or in respiratory distress
• Your rabbit is completely unresponsive or found collapsed
• Your rabbit has not eaten in more than 12 hours along with any of the above signs

Frequently Asked Questions

Is myxomatosis contagious to humans or other pets? No. The Myxoma virus is completely species-specific to lagomorphs (rabbits and hares). It cannot infect humans, dogs, cats, guinea pigs, or any other mammal species. There is no zoonotic risk to human family members. Other pet species in the home are not at risk. Only other rabbits need to be isolated when a case occurs.

Can a rabbit survive myxomatosis? Survival is possible in mild or attenuated cases, particularly with very early diagnosis and intensive supportive care. However, classic myxomatosis in unvaccinated domestic rabbits carries a mortality rate of approximately 95–100%. In Europe where vaccination is common, vaccinated rabbits that contract a breakthrough infection often survive. In the US, where no vaccine is licensed, intensive early care gives the best chance but the prognosis remains guarded to poor.

How much does treating myxomatosis cost? Supportive care for a rabbit with suspected or confirmed myxomatosis involves an initial exotic vet visit ($80–200), fluid therapy ($100–300 per day if hospitalized), antibiotics ($30–80 per course), and syringe feeding supplies. Exotic veterinary care is typically 1.5–2 times standard small animal costs. Total treatment for a rabbit receiving several days of intensive care can range $600–2,000. Humane euthanasia costs $80–200 and is often the most appropriate choice for severely affected rabbits.

Does myxomatosis occur in all US states? No. Myxomatosis is endemic in wild rabbit populations primarily in coastal California and coastal Oregon, where Sylvilagus populations serve as reservoir hosts. Sporadic cases outside this range occur when infected wild rabbits or their insects are transported, but the disease is not considered established elsewhere in North America. Rabbit owners in the western US face the highest ongoing risk, though all rabbit owners should maintain flea and mosquito control.

Why is there no myxomatosis vaccine in the US? A licensed myxomatosis vaccine (Nobivac Myxo-RHD Plus) exists in Europe and is in routine use. In the US, the USDA licensing process for rabbit vaccines has historically not been pursued by vaccine manufacturers for commercial reasons, as the rabbit vaccine market is small. Some rabbit owners in California import vaccines for use under veterinary supervision, but this remains off-label and is not widely accessible. This is an area of active advocacy within the exotic animal veterinary community.

What should I do if I find a dead wild rabbit near my property? Do not handle the carcass with bare hands. Wild rabbits can carry Myxoma virus, rabbit hemorrhagic disease virus, and other pathogens. Use gloves to dispose of the carcass in a sealed bag in the trash. Do not allow your domestic rabbits outdoors in the area until the source is identified. Contact your local wildlife authority if you find multiple dead wild rabbits — this may signal an outbreak of myxomatosis or RHDV2 in the local wild population.

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