Known throughout most of the world to be a highly contagious disease, myxomatosis is a generally fatal disease and affects the majority of rabbits. The disease is also known as myxi and is caused by a deadly pathogen called the Myxoma virus. Once infected the animal usually dies within a fortnight and both wild and domesticated rabbits are at risk from myxomatosis. The rabbits more susceptible to infection are those living outside since they are more likely to come into contact with the Myxoma virus than domestic indoor rabbits. This does not mean, however, that animals kept indoors are not at risk because they most definitely are.
The Mxyoma virus can be transmitted via direct contact with an animal infected by myxomatosis or indirectly via exposure to contaminated surfaces and insects, such as fleas. Swelling around the head area and the genitals are the most common form of symptoms which the rabbits will experience following contracting the disease. Myxomatosis is not known as a zoonotic disease and so this means it is not able to infect the human population. Vaccinations in the UK are highly recommended and encouraged to prevent, or at least reduce, the spread of this infectious disease.
It is recognised that both direct and indirect exposure to the myxoma virus can result in the spread of myxomatosis. Direct transmission consists of there being actual contact between an infected rabbit and another rabbit. However, contact with fomites is also known to be sources of infection. Contaminated surfaces including hutches, cages, hay, straw, water bottles, and food bowls are all in the list of possible fomites. Insects such as fleas and mosquitos have the ability to act as vectors and inoculate the virus into rabbits after acquiring it from infected animals.
All rabbit owners should ensure that they do not carry in the virus on their shoes or even on the feet of their other pets. This can be done without even knowing and so if the pet rabbits are unvaccinated then owners should attempt to not go in area where wild rabbits or unvaccinated domestic rabbits live. Adequate hygiene is very important at all times to prevent transmission and contact with unvaccinated rabbits should be discouraged. If wild rabbits are able to enter areas near domesticated animals then the pet rabbits should be kept in places where this cannot occur. For example, simply chicken wire placed around hutches to prevent contact.
Initially the disease presents itself in visible lumps. Characteristically, there is usually swelling and the lumps emerge around the face and there is mainly swelling around the genitals. A high temperature, lethargy and a loss of appetite are common results of infection from the myxoma virus. Sometimes, the loss of appetite can be due to the swelling around the face which can cause any feeding and drinking to be hard to achieve and stressful. Vaccinated rabbits show much milder symptoms and are more likely to recover.
Ocular discharge and conjunctivitis are observed in some cases. This may even lead to the rabbit going blind. Viscous and yellow pus will form and leave via the nose. Generally the rabbit will die within a fortnight but sudden death during the first days of infection may also be an occurrence. If not killed first by the virus, secondary infections such as pneumonia can result in a quicker death. Once diagnosed, most rabbits are euthanized to ease the suffering induced by myxomatosis.
Treatment and Prevention
There is no cure to treat unvaccinated rabbits infected with myxomatosis. Most are euthanized to reduce further suffering. In very mild cases, supportive therapy or intensive care may be given in addition to antibiotics to prevent or treat secondary infections although many unvaccinated rabbits die following infection. Vaccinated rabbits are more likely to survive if they have contracted the myxoma virus. In cases of infection affecting the vaccinated rabbit’s health then fluids are replaced, antibiotics are given to prevent possible secondary infections, feeding is sometimes administered through a tube and keeping it in a warm area will all be a part of the treatment plan.
As can be seen from the treatment plans, vaccinating rabbits is highly recommended and significantly reduces the incidence of fatalities. If unvaccinated it is almost certain that the rabbits will die. However, in Australia it must be noted that vaccination is against the law since an expanding population of immune wild rabbits is unwanted. Vaccination should not be at the same time, but a fortnight before or after, the viral haemorrhagic vaccine is administered.
Diagnosis and Prognosis
The rabbit is usually initially diagnosed by observing the signs and symptoms presented. The majority of results come from the dead body of the infected animal. Laboratory tests isolate and identify the myxoma virus. The prognosis for unvaccinated rabbits is poor with the large majority of them dying as a result of the disease, a secondary infection or from being euthanized. It is for this reason that many are vaccinated.