Wet Tail: Old Disease, New Cause

Wet tail, also known as proliferative ileitis (PI) or hamster enteritis, is considered a common disease of hamsters, but its incidence (number of new cases per year) and prevalence (number of cases at any time) are not known. As the name suggests, the main symptom is diarrhoea, leading to dehydration and matting of the fur around the tail and perineum. Up to 80% of affected animals will die, and it is not clear what effect (if any) treatment has upon outcome.

Hamsters are not the only animals to suffer from PI. Pigs, horses, deer and even ostriches develop disease with the same characteristic changes in the lining of the gut. For many years there has been debate over the identity of the organism responsible for the inflammation. E.Coli may occasionally be grown from hamsters with diarrhoea, but it is not associated with PI. Campylobacter species, including C.jejuni are frequently found in association with PI, but again, they are not thought to be the cause, as pure cultures of this organism do not reproduce the disease in healthy animals.

PI has puzzled microbiologists and epidemiologists for many years, but some recent research has identified a new player. In 1994, veterinary pathologists at Edinburgh's Royal (Dick) Veterinary School identified an agent that could transmit PI from pigs to hamsters. Three years later, scientists in the USA identified a bacterium named Lawsonia intracellularis as the causative agent in pigs. It has now been shown using DNA testing that the organism responsible for PI in hamsters is also of the genus Lawsonia, and may even be the same species, L. Intracellularis.

The implications for treatment of Wet Tail using new antibiotics are uncertain at present, but I will attempt to find out more from the institutions that carried out the research.

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