Myxomatosis is a devastating viral disease that kills pet rabbits. There is currently an outbreak going on in Santa Cruz County, California, where I live. It has been a very dry year, and as a result the streams aren’t flowing quickly, which leads to lots of mosquitoes. Mosquitoes can carry this virus from cottontail rabbits to domesticated rabbits. The virus can also spread by direct contact, and by other insects such as ticks and fleas.
While the myxomatosis virus only causes minor disease in wild cottontail rabbits, it is highly lethal to pet rabbits, with a reported mortality rate of 96-100%. Initial signs are seen three days after infection and can include reddened eyes with a milky discharge, lethargy, loss of appetite, and fever. Rabbits that survive this initial stage develop swelling of the eyelids, nostrils, lips, scrotum, vulva, anus, and ears. An opaque nasal discharge and labored breathing will commonly follow, leading to death within 7 to 14 days. Unfortunately, there is no effective treatment for myxomatosis; our only options are to provide supportive care and hope the bunny gets through it, or to euthanize.
While there is an effective vaccine against this disease, it is not licensed for use in the United States. The FDA won’t allow the importation of this vaccine from Europe because it also vaccinates against Rabbit Hemorrhagic Virus, a disease that we (usually) don’t have here in the U.S.
The only way to prevent myxomatosis here in the coastal northwestern U.S., then, is to prevent exposure. Assess your home and environs. Are there mosquitoes around? Are there wild cottontails around? If so, keep your bunnies indoors at all times. If not, it still pays to be cautious. Carefully enclose outdoor hutches with mosquito screens. Make sure that your rabbit is either indoors or behind mosquito netting during the highest mosquito activity time periods, dawn and dusk. It is also wise to make sure that all bunnies that go outside receive a monthly dose of the flea control product Advantage.
Remember, myxomatosis is highly contagious and can be rapidly fatal. If you see any symptoms of myxomatosis in your rabbit, make sure to isolate it from other rabbits and call your veterinarian immediately.
Hilary Stern DVM © 2014