Myxomatosis is caused by the myxoma virus, a poxvirus spread between rabbits by close contact and biting insects such as fleas and mosquitoes. The virus causes swelling and discharge from the eyes, nose, and anogenital region of infected rabbits. Most rabbits die within 10-14 days of infection however highly virulent strains of the myxoma virus may cause death before the usual signs of infection have appeared.
Myxomatosis was introduced to Australia in 1950 to reduce pest rabbit numbers. The virus initially reduced the wild rabbit population by 95% but since then, resistance to the virus has increased and less deadly strains of the virus have emerged. Pet rabbits do not possess any resistance to myxomatosis, and mortality rates are between 96-100%. With such a poor prognosis, treatment is not usually recommended.
Vaccination against myxomatosis is not permitted in Australia, so limiting exposure is the best preventative measure.
- Put mosquito netting around your rabbit’s hutch even if indoors (this will help to prevent flystrike as well).
- If your rabbits are allowed to exercise outside, avoid letting them out in the early morning or late afternoon when mosquitoes are more numerous.
- Please talk to your veterinarian about flea prevention for rabbits. You can use Revolution® (Selamectin) or Advantage® (Imidocloprid) for flea prevention, but you must check first with your veterinarian for dosages. Do not use Frontline® (Fipronil) as this is often fatal to rabbits.
The Australian Government maintains that, because the myxomatosis vaccines are modified live-virus vaccinations (meaning they contain weakened forms of the virus), the weakened viruses in the vaccine could spread from domestic rabbits to the pest rabbit population, possibly immunising them against myxomatosis. RSPCA Australia has repeatedly called for a review of available myxoma virus vaccines and a scientific assessment of their likely impacts in the Australian setting. We would like to see action taken to ensure that all domestic rabbits can be protected against contracting myxomatosis.