Myxomatosis
How was it introduced?
Myxomatosis is a highly contagious severe viral disease caused by the myxoma virus (a species of poxvirus). The disease was first reported in the late 19th century, when a stock of laboratory rabbits in Uruguay succumbed to it. Much later, the original source was found to be Brazilian wild rabbits, although they only suffered a mild form of the disease. It’s widely known that myxomatosis was introduced to Australia in 1950, to control the wild rabbit population.
As for Europe, a French physician, Paul-Felix Armand-DeLille, is thought to have been responsible for wiping out a large proportion of Western Europe’s rabbits. In 1952, he acquired the virus from a laboratory and inoculated two rabbits, which he released on his estate in northern France, as a means of wild rabbit control. Within a few weeks, 98% of the rabbits on his land had been eliminated. However, he’d failed to realise the disease could be spread by insects – within four months, an infected rabbit corpse was found 30 miles from his estate, and by 1954 the disease had killed 90% of the wild rabbits in France. Myxomatosis spread rapidly, destroying rabbit populations across Europe.
The first recorded outbreak of myxomatosis in the UK was in 1953, at Bough Beech near Edenbridge, Kent, with mortality rates of over 99.9% (it had been noticed that rabbits in the area had been suffering and dying from an unusual disease, which was officially diagnosed as myxomatosis on 13 October, 1953). Efforts were made to confine the outbreak, but a second outbreak was recorded in Robertsbridge, East Sussex, on 27 October. By 1955, the disease had killed around 95% of the country’s rabbits, was having an impact on the balance of nature (see The origin and spread of myxomatosis, with particular reference to Great Britain, by Harry V. Thompson). Farmers had obtained infected rabbits or corpses and placed them in burrows to control the wild rabbit population. This practice was banned under the 1954 Pests Act.
Myxomatosis has killed tens of millions of wild rabbits. Despite many wild rabbits developing a resistance, several deadly strains of myxomatosis still exist widely, and continue to kill many wild rabbits. It is found throughout the UK.
Myxomatosis also kills many pet rabbits each year, despite availability of a vaccine.
Myxomatosis does not affect other pets or humans.
How do rabbits become infected?
Myxomatosis spreads rapidly among wild rabbits, and can be passed on to pet rabbits through:
· Blood-sucking insects such as fleas, ticks, mites, and mosquitoes, which have previously bitten an infected rabbit.
· Contact with an infected rabbit.
· Contaminated objects.
What are the symptoms?
The incubation period for myxomatosis is 8-21 days, depending on the strain.
Exposure to the virus may cause changes in rabbits’ behaviour and appetite. The first symptoms often affect a rabbit’s eyes, nose, and genitals, but symptoms may include:
· Swelling, redness and/or ulcers around the eyes, nose, ear skin, lips, and genitals.
· Runny nose.
· Eye discharge.
· Blindness (caused by inflammation of the eyes).
· Swellings on skin.
· Laboured breathing.
· Lack of appetite.
· Lethargy.
· Fever.
· Depression
Vaccinated rabbits usually experience a milder form of the disease, and recover with treatment.
For unvaccinated rabbits (and wild rabbits), most cases are fatal, with the rabbit suffering a painful death, usually within fourteen days. Some cases have been fatal within 48 hours of rabbits displaying symptoms, whereas other rabbits have survived for several weeks before dying. Cause of death is often a secondary bacterial infection, eg. pneumonia.
Vaccination
Vaccinating rabbits is the best way to protect them against myxomatosis. All rabbits, including those kept indoors, should be vaccinated. We have access to a combined vaccination for myxomatosis, RVHD1, and RVHD2, which can be given to a rabbit from five weeks of age. Annual boosters are essential.
Occasionally, vaccinated rabbits are infected with a mild form of myxomatosis (which causes pox marks on their nose, face, and ears), but the prognosis is much better than for unvaccinated rabbits, with support of veterinary treatment.
Other preventative measures
As vaccinated rabbits can sometimes be infected, additional measures should be taken to reduce the risk of myxomatosis:
· Standing water attracts mosquitos, so it’s a good idea to keep rabbits away from it. Water butts should be covered, and a layer of cooking oil can help to eliminate mosquito larvae from other water containers.
· If you’ve been in an area where wild rabbits graze, wash hands and clothes before entering your pet rabbits’ environment.
· Keep rabbits’ bedding and litter fresh, and clean their living area regularly.
· Ensure biting insects are kept out of rabbits’ area (eg. use insect screens/netting).
· Never allow pet rabbits to be in proximity to wild rabbits.
· Ensure wild birds and rodents cannot enter rabbit enclosures.
· Ensure pet cats and dogs are regularly treated for fleas (consult a vet about rabbit-friendly treatments).
· Buy hay from a trusted source – if you buy from a farmer, check that no cases of wild rabbits with myxomatosis have been reported/seen.
· Buy dust-extracted hay or kiln-dried grass.
Most importantly, seek urgent veterinary care if a rabbit shows any signs of myxomatosis.
There is no cure for myxomatosis. For an unvaccinated rabbit, the disease is often severe, response to treatment is poor, and the vet may recommend euthanasia. For vaccinated rabbits, full recovery is possible with supportive veterinary care, including:
· Antibiotics (to prevent infections).
· Warmth.
· Fluids.
· Nutrition.
Remember: ALL rabbits require vaccination against myxomatosis!
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ALL rabbits, including houserabbits, require vaccination. |
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