28/11/2015

Myxomatosis (Myxoma virus) is a highly contagious disease seen in the European and Domestic Rabbit. European Brown Hares can also occasionally show clinical signs. The seasonal prevalence for Myxomatosis is October to May. The Myxoma virus only infects rabbits.

Transmission is via direct contact, aerosol (large outbreaks), biting insects (mosquitoes, fleas, mites and biting flies) and fomites (spiny thistles).

Prevention in Australia is via housing inside/under mosquito netting, not having rabbits living near sitting water sources where insects like to breed, reducing the wild rabbit population and controlling insect vectors. There is no vaccine available to date in Australia.

Disease in pet rabbits is often the classical form, with death resulting within 1118 days.

Prognosis of survival in pet rabbits is reported to be less than 1%. There is no commercial diagnostic test for Myxoma Virus available in Australia. Confirmation of infection can be clinically confirmed with the presence of thickened ears, swollen eyes and swollen genital region. If we are not confident on a diagnosis of Myxomatosis, we may prescribe 3-4 days of pain relief, anti-inflammatories to reduce the swelling and antibiotics to relieve secondary infections.

Partial innate immunity can be seen in wild rabbits, and rarely in pet rabbits. This can result in a chronic form of Myxomatosis with multiple black raised skin lesions. Prognosis of survival of this skin form of Myxomatosis, may be more favorable compared to the classical form but secondary pneumonia is common. Biopsy of suspected lesions is diagnostic.

Treatment of pet rabbits is often futile and poses moral questions regarding protracted suffering. Treatment requires full isolation, intravenous fluids, pain relief, assisted feeding (syringe feeding and nasogastric tube feeding in later stages) and 24 hour care.

Treatment is rarely successful. Supportive treatment is often required for 14-18 days and carries an extremely poor prognosis. Aggressive treatment should be instituted as early as possible at the first signs of disease; minimal treatment is nearly always futile.

Due to the number of rabbit patients at the clinic combined with how contagious the virus is, we are unable to offer hospitalised treatment in our clinic. Please seek supportive treatment at the emergency center.

Disinfection of hutches, food bowls and immediate surroundings is required prior to the introduction of another rabbit. Recommended disinfectants include those with a broad spectrum of activity such as 10% household bleach. Thorough rinsing is advised to prevent ingestion. It is difficult to ensure complete disinfection of concrete/wooden hutches, carpet and if vegetation/soil is present.

Replacement rabbits are not advised for at least 4 months. This not only allows reduction of the virus in the immediate environment but also a reduction in neighboring wild rabbit populations/insect vectors due to seasonal changes.