There is a common and dangerous assumption among rabbit owners in NSW: that the colder months bring relief from mosquito-borne illness. That once summer is over, the risk drops.
It does not drop enough.
Myxomatosis is active in the Illawarra year-round. Mosquitoes still feed in autumn and early winter, especially on mild evenings and near water. Fleas, which are an equally efficient vector for myxomatosis transmission, have no off-season at all.
If your rabbit is unvaccinated and unprotected, May is not a safe month. Neither is June. The disease does not take a winter break, and by the time symptoms appear, the window for meaningful intervention is already closing.
This article explains what myxomatosis is, how to recognise it early, what the transmission routes look like through the cooler months, and what to do if you have any concern about your rabbit.
What Is Myxomatosis?
Myxomatosis is a viral disease caused by the Myxoma virus. It was deliberately introduced into Australia in the 1950s as a method of wild rabbit population control, and it remains endemic across most of the country, including coastal NSW.
In wild rabbits, the disease causes high mortality. In domestic rabbits, it is almost universally fatal without rapid veterinary intervention, and even with treatment, survival is uncommon once the disease is advanced.
There is currently no registered myxomatosis vaccine available in Australia. That distinction matters: unlike calicivirus (RHDV), where vaccination is available and strongly recommended, myxomatosis prevention relies entirely on reducing your rabbit’s exposure to the vectors that carry it.
How Myxomatosis Spreads: It Is Not Just Mosquitoes
Most owners know that mosquitoes transmit myxomatosis. Fewer realise that fleas are an equally efficient vector, and that transmission can also occur through direct contact with an infected animal, contaminated equipment, or even through flies landing on open wounds or eyes.
The main transmission routes:
- Mosquitoes biting an infected wild rabbit and then biting your pet
- Fleas, including rabbit fleas and cat and dog fleas, carrying the virus between animals
- Biting flies acting as mechanical vectors
- Direct contact with an infected rabbit (wild or domestic)
- Indirect contact via contaminated hutch materials, food, water bowls, or clothing
The implication for the cooler months is this: while mosquito activity does reduce, it does not stop. Evening temperatures in the Illawarra through May and June remain mild enough for mosquitoes to be active, particularly near Lake Illawarra, low-lying gardens, and any area with standing water. And fleas, which are the vector owners most underestimate, remain active regardless of temperature.
An outdoor rabbit, or an indoor rabbit housed near a fly screen with gaps, remains at meaningful risk through winter.
Recognising Myxomatosis: Symptoms by Stage
Myxomatosis progresses in stages. The earlier it is identified, the more options are available. Owners who can recognise the early signs have the best chance of getting their rabbit seen before the disease becomes irreversible.
Stage 1: Early signs (days 1 to 5 after infection)
These early signs are subtle and easy to dismiss. Do not dismiss them.
- Mild swelling or puffiness around the eyes, nose, ears, or genitals
- A slightly watery or sticky discharge from one or both eyes
- The rabbit seeming quieter than usual or less interested in food
- Mild lethargy without obvious cause
At this stage the rabbit may seem “a bit off” rather than critically unwell. This is the window where veterinary assessment is most valuable. If you notice any of these signs, contact your rabbit vet immediately.
Stage 2: Acute phase (days 5 to 10)
- Pronounced swelling of the eyelids, often severe enough to partially or fully close the eyes
- Thick, purulent discharge from the eyes and nose
- Large, raised lumps (myxomas) appearing on the face, ears, and body
- Swelling of the genitals
- Rapid deterioration in body condition
- Loss of appetite, significant lethargy, difficulty breathing
By this stage the diagnosis is usually visually obvious, but the rabbit is in serious distress and the prognosis has worsened considerably.
Stage 3: Terminal phase
- Complete blindness from swollen, sealed eyelids
- Severe respiratory distress from lung involvement
- Inability to eat or drink
- The rabbit is moribund
At this stage the most humane intervention is usually euthanasia to prevent suffering. This is an outcome every owner wants to avoid, and it is why early recognition and immediate veterinary contact are so critical.
What to Do If You Suspect Myxomatosis
Do not wait and see. Myxomatosis deteriorates rapidly and there is no benefit to monitoring at home for a day or two. If your rabbit is showing any of the early signs listed above, the right action is to call your vet today.
Our team provides rabbit illness and injury care and we have a strong interest in rabbit medicine. If you are in the Dapto or wider Illawarra area and your rabbit is unwell, call us on (02) 4261 9838.
If your rabbit deteriorates outside of business hours and needs emergency assessment, contact your nearest emergency veterinary facility immediately. Do not wait until morning.
When you call, tell us:
- The specific symptoms you have observed and when they started
- Whether your rabbit has had any possible exposure to wild rabbits, other rabbits, or outdoor areas
- Whether your rabbit’s flea prevention is current
- Whether your rabbit has been vaccinated for RHDV (calicivirus), even though this does not cover myxomatosis
Prevention: What Actually Works
Because there is no vaccine available in Australia for myxomatosis, prevention depends on management. The following measures reduce risk significantly.
1. Mosquito-proof the living environment
- Use fine-mesh fly screens on all hutch openings. Standard fly screen mesh is not fine enough to exclude small mosquitoes; look for screens rated for mosquito exclusion.
- Hang mosquito netting over outdoor hutches during evening and overnight hours, when mosquito activity peaks.
- Avoid housing rabbits near standing water, ponds, or low-lying areas where mosquitoes breed.
- Bring outdoor rabbits inside during dawn and dusk, when mosquito activity is highest.
2. Maintain rigorous flea control
This is the step most rabbit owners skip, particularly in winter.
- Treat your rabbit with a vet-approved flea prevention product. Not all flea products are safe for rabbits; many products designed for cats and dogs are toxic to rabbits. Ask your rabbit vet before applying anything.
- Treat any dogs or cats in the household for fleas. An infested cat or dog is a flea reservoir that puts your rabbit at risk even if the rabbit never goes outside.
- Wash and replace hutch bedding regularly.
3. Prevent contact with wild rabbits
Wild rabbits in the Illawarra carry myxomatosis. Any outdoor area where wild rabbits have been present is a risk environment. Do not allow your domestic rabbit to graze in areas frequented by wild rabbits, and do not allow direct contact.
4. Maintain good general health
A rabbit in good body condition, eating a correct diet (primarily hay, leafy greens, limited pellets), and free from dental disease and other underlying conditions has a stronger immune response. Regular health checks with a rabbit-knowledgeable vet allow early detection of any issues affecting your rabbit’s overall resilience.
What About RHDV Vaccination? (Calicivirus)
Rabbit owners sometimes conflate myxomatosis and RHDV (Rabbit Haemorrhagic Disease Virus, also called calicivirus). They are different diseases with different prevention strategies.
RHDV can be vaccinated against in Australia. Vaccination is strongly recommended and should be kept up to date annually. In NSW, multiple strains of RHDV are present in the wild rabbit population, and even indoor rabbits are at risk because the virus can be carried on clothing, shoes, and insects.
Myxomatosis cannot currently be vaccinated against in Australia. Prevention is entirely through environmental management and flea control.
For detailed, current information on RHDV strains and surveillance in NSW, the NSW Department of Primary Industries maintains a rabbit haemorrhagic disease virus resource page that is updated as new strain detections occur.
If your rabbit is not vaccinated against RHDV, booking a vaccination appointment is urgent. Both diseases pose serious and often fatal risk to unprotected domestic rabbits, and they can circulate simultaneously.
A Note on Autumn and Early Winter Risk in the Illawarra
The Illawarra’s coastal climate means the shoulder seasons are more dangerous than owners often expect. The combination of mild overnight temperatures, proximity to Lake Illawarra and its surrounds, and the region’s significant wild rabbit population creates conditions where myxomatosis transmission remains possible well into June.
We see myxomatosis cases outside of summer. Not many, but we see them. And because the disease progresses so quickly, each one that reaches us in the acute or late stages represents an owner who did not realise the risk was still present.
If your rabbit lives outdoors, or has any access to outdoor spaces, please review your prevention measures now rather than in response to a sick animal.
Book a Rabbit Health Check
The best time to assess your rabbit’s protection and general health is before a problem develops. Our team has a genuine interest in rabbit medicine and surgery, and we see rabbits as the specialist patients they are, not as an afterthought.
A rabbit health check gives us the opportunity to:
- Review and update RHDV vaccination status
- Assess current flea prevention and recommend safe, rabbit-appropriate products
- Check body condition, dental health, and gut motility
- Discuss housing and environmental risk factors specific to your setup
- Answer any questions about myxomatosis prevention for your rabbit’s situation
Visit our rabbit care page for more information, or call us on (02) 4261 9838 to book.
If your rabbit is unwell right now, do not wait for a routine appointment. Call us today, or if it is outside business hours, seek emergency veterinary care immediately through our illness and injury service information.
