Hamsters are fastidious groomers. While washing is a big part of his grooming process, so is scratching. This means scratching is not necessarily a sign that something's wrong -- unless the intensity and frequency of scratching has grown a lot over a course of a few days. If the scratching is happening in conjunction with conditions such as skin irritation or hair loss, you might have a problem in your hands.
Check for signs of mites. These include hair loss, dry scaly skin and constant, intense scratching. If you look closely, you should be able to see mites on your hamster's skin. They usually look like small black dots that are constantly moving and changing position over the skin. Somewhat similar to fleas except that mites are much, much smaller -- like tiny dots. You can buy anti-mite medication from any pet store or from your vet.
Move the hair away and see if the skin looks red and irritated. This could be a sign of allergies. This can be harder to fix, because you'll first need to identify what your furry one is allergic to. According to Hamsterific, many cases of allergy are connected to bedding, so try changing the kind you use -- but not cedar -- and see if that makes a difference in the itching. If you changed something in your hamster's environment in the weeks before he scratching started, such as the food, the bedding or the product you use to clean the cage, it may be the cause. Go back to what you were using before and see if that makes a difference.
Check for mange. Mange is a highly contagious skin disease that can pass to a hamster from other animals -- especially dogs. If you touched an animal with mange and came home and touched your hamster before washing thoroughly, you might have passed on the infection without realizing it. Mange causes extreme itching, which usually leads to scabs and very red, sometimes bloody skin. It also causes hair loss. Mange treatment requires a visit to the vet.
- Hamster image by Annekathrin Kohout from Fotolia.com