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Myxomatosis In Rabbits

Answers to the most common FAQs

How do pet rabbits get Myxomatosis?

The most likely source of infection for pet rabbits is via biting insects and other arthropods, mainly fleas, but also flying biting insects such as mosquitoes - they transmit the virus via their mouthparts, from local wild or domestic infected rabbits. Also possible - if wild rabbits have access to the garden, or can get close, e.g. through a mesh fence or run - is direct infection from rabbit to rabbit via respiratory tract secretions. Of course, once one rabbit in a group is infected, this route is also a worry with regards to the infection of the other rabbits.

What's the Incubation Period?

The incubation is variable, depending on the route of infection and thus the site of disease. Skin lesions (from biting insects) may be seen from as early as 4 days, becoming very definitely noticeable by 10-14 days. One can expect by that point that the eyelids will be noticeably swollen, and if biting insects are the route of infection, one is probably out of danger of infection at that point, as long as no infection has been introduced after the suspected date of the initial case.

Lung infection can be seen in group-housed rabbits where aerosols spread into the environment, leading to inhalation and subsequent pneumonia, though this may not be noted until up to 20 days after infection. This is much less common than the typical skin, face and eyelid swellings.

Does It Spread?

Not necessarily, especially if they are rapidly separated, or steps are taken to reduce insect spread. Individual immunity obviously varies, otherwise all wild rabbits would have succumbed to it and died by now. Previous infection or vaccination will help afford immunity, but immunity is not long-lived, and not absolute. Different rabbits will have different health statuses, and be more or less susceptible. However, given the highly infectious nature of the disease, and the generally poor level of immunity present, the likelihood of infection of all in contact is highly likely.

Should Infected Rabbits be Put to Sleep?

This depends on the virulence of the strain, the form of the disease, and the immunity of the rabbit. If the lesions are dry and nodular, and quite discrete, this cutaneous Myxomatosis carries a good prognosis, and I would definitely not put such rabbits to sleep. If there is generalised disease, with swelling of the head, including ears and eyelids, and genitals, with or without lung involvement, then the outlook is far worse. If these rabbits have been vaccinated, they have a better chance of survival. Treatment with antibiotics (for secondary Pasteurellosis and other bacteria), anti-inflammatories, nebulisation and drugs to improve respiratory function (to help breathing), nutrition, fluid therapy, and raised environmental temperatures (to 85F/29.5C) may effect a cure in a small number of cases, but this has to be weighed against the distressing and uncomfortable nature of the disease, and the welfare problems if a decision is made to treat. It is a horrible way to die, and extremely unpleasant for anyone watching it.

Should An Affected Rabbit Be Isolated?

If a decision is made to treat one rabbit, it needs to be isolated from the others. Whilst that adds to that rabbit’s stress (and that of the healthy rabbits), the risks of infecting the others are significant, even if diligent insect vector removal is performed.

Treatment ideally involves raising the ambient temperature to 85F/29.5C for the infected rabbit, and that is not comfortable for healthy rabbits.

Ideally, the remaining partner or group members should also be isolated from other rabbits in case they are incubating the disease and are able to transfer it to rabbits in the next run/enclosure. This can happen either by direct contact or close proximity to mechanical vectors. If all were infected at the same time, and one or more have lesions, the others may simply be a few days behind and therefore potentially infective, very soon. They should all be treated for fleas, placed in a separate airspace to those infected, and definitely to those who haven't yet been exposed.

How Do I Prevent It?

Vaccination is the mainstay of preventative healthcare. Regular vaccination, either every 6 months via the intradermal and subcutaneous routes, or every year by the subcutaneous route alone, is advised.

Spot-on and Fly Strike treatments are advised, given two days apart. Insect control is vital. There are products available that repel and kill biting insects and fleas, preventing the spread of Myxomatosis. Certain treatments don't need the flea to bite in order to be killed by the active treatment, but it can take up to 12 hours to kill fleas, which permits them time to attach and spread Myxomytosis. Environmental control, using insecticides, insect repellents and physical barriers e.g. fine mesh on windows and doors, mosquito netting etc. is helpful, especially at times of the day when they are active e.g. dusk.

Preventing other domestic pets from bringing either wild rabbits, or their fleas, into the home or garden, is important. If they hunt wild rabbits, rabbit fleas may be carried by dogs and cats. They typically line up on the edge of the ears. Domestic pets should be examined, treated, and not allowed near rabbits until it’s certain that there are no fleas present.

Cleaning an environment (shed/hutch/paving/grass) after it's hosted infected rabbits:

Inside fleas, the disease can survive for up to about 4 months and the survival times in the wider environment are much smaller than that. To be sure, however, you should wait a minimum of 4 months before obtaining new rabbits. Although stringent flea control and disinfection should be sufficient to minimise the risk, new infections are still possible from fleas and flying insects that gain access, so ongoing control and vaccination is vital.

Will My Rabbit Be Immune After a Myxi?

Should I still vaccinate to cover the VHD risk?

This is controversial, and it’s difficult to give firm advice here. I would prefer to err on the side of caution. Some references suggest lifelong immunity following recovery from natural infection, others suggest absolute immunity for several months. Without performing antibody testing, it is best to assume that all animals are susceptible, and to afford the highest level of protection against both, I would recommend vaccinating with both Myxomatosis and RHD vaccines. The Myxo-RHD vaccine carries warnings to the effect: in rabbits with existing immunity to Myxomatosis, there may not be a good level of post-vaccination RHD immunity. In such cases, a single RHD vaccine may be given 2 weeks after the combined vaccine.