Wet-tail

Wet-tail or proliferative ileitis, is a disease in rodents kept in cages, mainly hamsters, but can include rabbits, gerbils, rats, and mice. It is caused by stress. Even with treatment, the animal can die within 24–48 hours. Baby hamsters are much more likely to get the disease than older hamsters. It commonly is found when the hamster is being weaned at about four weeks of age.
Causes.
Wet-tail is a disease in the animal's intestines caused by the bacteria, "Lawsonia intracellularis". Wet-tail is stress related. The stress can be caused by:
Symptoms.
The symptoms may not appear for several days. The main symptom is the animal has a wet tail, matted with faeces. Other signs of the disease are: 
Treatment.
There are drugs to treat wet-tail which can be bought from pet shops. A vet may choose to give the animal other drugs. The sick animal should be kept in a cage by itself so that others do not catch the disease.