Itchy Dwarf Hamster! Why?

Question
I just recently adopted an 8-month old dwarf hamster from a boy who never cleaned its cage. Now that I have inspected it closely, I observed that it is constantly itching all over, including its ears! I thought it might be an allergy to this hamster spray I had purchased, however, I have used it before and there was no itching. Taking special precautions, I rinsed the hamster with water in case it was allergic to the solution.

What are all of the possible reasons for the itchiness of my hamster?
Should I leave it alone for a couple of days before taking any kind of action?


Answer
Considering the level of hygiene you observed from the former owner, I would not doubt it a bit if the hamster had a mite or possibly flea infestation.  If it's fleas, you should definately be able to tell.  It might be a bit more difficult on a black or umbrous colored hamster, but if you pick them up and blow on the hair of the stomach (which is generally lighter and thinner) to part it, you'd see the fleas or the "flea dirt" which is actually just bits of digested blood.  (Yuck!)  Sometimes you may be able to see some mites this way too, but you'd have to look very closely, have very good light, or have excellent eyesight (or all three, depending on the mite!).  There are over the counter sprays available to treat mite and flea infestations in hamsters.  I have never used them, but I know they are out there.

Another possible explanation is the type of bedding used.  The oils in cedar and pine are major irritants (cedar more so than pine, but pine can still cause allergic reactions) to small animals' skin and respiratory tracts, which is why I always recommend aspen shavings or Carefresh.  Some people prefer the Carefresh because they can make nice nests out of it and it absorbs wetness and odors so well, some people prefer the aspen because they think the Carefresh is too dusty.  On my own hamsters, I use the Carefresh.

You can try the mite spray available at your local pet supply store, or you can go directly to your veterinarian.  If it is a mite infestation, likely your veterinarian will have something that works 100 times more effectively than anything you could get from a pet supply store, and depending on the type of mite they sometimes have treatments that work with only one application or oral dispension.  Which is nice when working with small animals that tend to start resenting you very quickly if you're constantly doing horrible things like medicating them.  :)