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.
There are two vaccinations against myxomatosis, however these are not available in Australia. Thus the only way to prevent infection is to protect your pet rabbits from biting insects such as fleas and mosquitoes. 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 vet about flea prevention for rabbits. You can use Revolution (Selamectin) or Advantage (Imidocloprid) for flea prevention, but you must check first with your vet for dosages. Do not use Frontline (Fipronil) as this has been associated with severe adverse reactions in rabbits.
If your pet rabbit does develop myxomatosis, your vet will advise the best course of action, which may be euthanasia. Treatment is rarely successful, even if commenced early in the infection and the course of disease is very painful and stressful. Thoroughly disinfect your rabbit hutch, water bottles and food bowls with household bleach, rinsing it off so that it cannot be ingested by any other rabbits. Bringing a new rabbit home is not recommended for at least four months after a case of myxomatosis as the virus is able to survive in the environment for some time.
Owners are reminded to vaccinate their rabbits against rabbit haemorrhagic disease (RHD), especially as a new strain known as RHDV2 which has been reported as causing deaths of domestic rabbits. The current RHD vaccine may offer only limited protection against this strain but additional precautions can be taken to help minimise risks.
Further information on myxomatosis is available at this link: http://www.agriculture.gov.au/animal/health/myxomatosis-vaccine