What is it?
Myxomatosis is a fatal disease in rabbits caused by the myxoma virus; it is similar to the smallpox virus in people. It was first discovered in England in the 1950s where it came across the Channel from France (where it had been released illegally). It has been endemic in the UK rabbit population since then.
There are a couple of different strains of the disease; depending on the strain it usually causes swelling under the skin (around the eyelids, face, genitals and bottom). However, some strains cause signs of lung disease with less severe skin swellings.
Why is it important?Myxomatosis is endemic within the wild rabbit population of the UK and is therefore a risk for our pet rabbits. It is spread either via direct contact with infected wild rabbits or by insect vectors (carriers), often fleas or mosquitos.
What’s the risk?
All rabbits are at risk, whether indoor or outdoor. This is due to the disease having vectors which can be carried on clothing or even fly into homes.
There appears to be a seasonal influence on the disease in wild rabbit populations, with levels of disease being greater when flea populations are at their highest - i.e. in the spring. The location of high-risk areas of disease alters each year and is dependent on how susceptible the local rabbits are and their level of immunity.
What happens to the rabbit?
Infection travels around the body, affecting cells within it. The first sign is approximately 4-5 days after infection and is usually a small skin swelling which then enlarges over a period of around 10 days. At this point the eyelids are often swollen with pus-like discharge from the eyes. Swellings form around the ‘top and tail’: the lips, nostrils, eyelids, ears, genitals and anus. Some strains can result in pneumonia (severe lung disease) and can take 3 weeks from infection to develop. Rabbits that do survive the infection are often infertile for a long period of time due to the swelling affecting their genitals.
The virus usually results in death of the infected rabbit - this can be due to secondary infection (e.g. pneumonia), the infection itself, or due to being weak as a result of illness and being killed in the wild.
The rabbits that survive infection may develop immunity for a period of time. There is also a genetic link with immunity to infection in the wild.
How do you know what’s going on?
The following signs of infection may be seen:
What can be done?
In some very rare cases, myxomatosis can be successfully treated. This depends on the strength of the immune system of the rabbit and other underlying or secondary disorders. The prognosis is best when the rabbit has been previously vaccinated; even if immunity has waned, the immune system may, with help, be able to rally against the virus. Treatment where appropriate must be prescribed by a vet and involves:
What can I do to protect my pet?
Vaccination is available against the disease; the most recent vaccine provides 12 months of immunity to myxoma virus. No vaccine is 100% effective against a disease. However, it has been proven that in those few vaccinated rabbits that contract the disease, the majority will survive with appropriate treatment.
It is therefore recommended that all rabbits are vaccinated against myxomatosis (alongside RVHD1 and RVHD2). Any signs that may be associated with the virus should be examined immediately by a vet. Please remember that due to the way the virus is spread, indoor rabbits are still at risk and still require vaccinations.