Hello,
If this is indeed Wet tail the over the counter medications from a Pet shop is useless. I do not believe any Vet will dispense a medication without seeing the Hamster. The Hamster cannot take just any antibiotic because of a sensitivity to meds. and no Vet will give Medication to animal that they have not seen. It would put their license in jeopardy. I can recommend there may be a Hamster rescue in your area that can help treat the Hamster. There is also your local animal shelters. If you would like me to try and locate a Hamster rescue for I can try with a state and city location. I wish I could give you better news. You can give Plain Pedilayte via syringe to help prevent dehydration. I am sorry if this is not what you were hoping for. Please do not accept unless I have been able to help you. I can always opt out and have another Expert try to assist you. Joan
http://www.hamsterific.com/IllnessGuide.cfm#WetTail
Veterinary Technician
I am Vet Tech. for 30+yrs. who works with all animals. I do alot of rescue work with small animals.