VET’S DIARY: Where the end does not not justify the means

THERE is no getting away from the fact that, in many things that he does, man causes no end of problems, writes Dominic Plumley.

It doesn’t really matter what the sentiments were, sometimes the means just don’t justify the ends and one such example is myxomatosis.

This most debilitating of diseases is caused by a myxoma virus, one of the poxviruses, and was first observed in laboratory rabbits in South America late in the 19th century.

As with many of the poxviruses, the infected rabbit develops severe skin swellings around the anus, genitalia and head, most characteristically the eyelids. Unable to see and often also finding it difficult to eat due to oral lesions, individuals rapidly become slow and weak and consequently in the wild become more exposed to predation if they don’t starve to death.

The virus was deliberately introduced into Australia in 1951 to control the large population of wild rabbits with fairly devastating effect.

A year later it was illegally introduced into France from where it spread to the UK by the following summer, as well as much of the rest of Europe.

Since then it has become a pretty much permanent threat to both wild and domesticated rabbits.

The virus is transferred from animal to animal by blood sucking insects, most commonly the rabbit flea within colonies and individuals in close contact. However, there are a number of other insect vectors that ensure that even individuals that are isolated from direct contact with other rabbits still remain at risk from the disease.

In spite of the devastating effect that infection can have on the wild population, with extremely high levels of mortality, often after prolonged and painful illness, some individuals survive and develop immunity to the virus.

As was found in Australia, wild populations will recover until large numbers again become susceptible to infection and the whole cycle repeats itself once more.

As viruses go, the poxviruses tend to stimulate the immune system in such a way that generates good immunity and consequently lend themselves well to the development of protective vaccines; demonstrated very nicely by the successful use of the smallpox vaccine to completely eradicate a disease that once killed thousands of people.

To this end, there is a commercially available vaccine for domesticated rabbits that provides good protection against the disease.

Unfortunately, the immune system of the rabbit does not have a great memory and in situations of high levels of challenge, vaccination has to be repeated every six months.

Of course, there are large numbers of pet bunnies about that are not vaccinated. Usually these have been bought from pet-stores for children – complete with hutch – and are plonked into the garden with little thought of the consequences.

As already mentioned, some individuals will recover but these are few are far between and most infected domesticated rabbits end up being euthanised on welfare grounds.

Though I haven’t seen that many infected wild rabbits about, there must be high levels of the virus in the environment because between our surgeries in Alnwick and Morpeth we have had to deal with 20-plus pet bunnies with myxomatosis in the last three or four weeks, nearly all of these ending sadly.

Invariably, where there is more than one rabbit in the household, all individuals eventually contract the disease, sometimes with several weeks of incubation between cases.

This of course only serves to compound the emotional distress, lulling the owners into a false sense of security that they have got away with only one affected individual.

It is pretty difficult to maintain isolation from all biting insects, though obviously pet bunnies in more urban situations would tend to fair better than those in rural households.

Ultimately the only protection is vaccination and a risk assessment is done to determine whether re-vaccination should be every six months or annually.

Failing this the only other option is to choose a different species of pet such as a guinea pig.