Hamsters are rodent pets beloved for their furry cuteness, so seeing his fuzzy coat marred with bald spots and patches can be troubling. Several things could cause hair loss in your hamster, and most of them are treatable.
Your hamster's hair could be thinning due to allergies, mites, dermatitis, fungal disease or Cushing disease, a more serious condition that usually occurs in older hamsters. Other signs of Cushing disease include scabby, crusty or darkened skin, as well as increased thirst and hunger. It's important to visit a vet who specializes in small animals so he can test your pet for mites that cause mange, and give you the proper medicine and care regimen needed to clear up the problem. This might include antiobiotics, antifungals, flea or heartworm medication, depending on the diagnosis. If tests for mites and diseases come back negative, your hamster might be allergic to the bedding or cage filler you're using.
If your hamster is chewing and pulling out his own fur, rather than it just falling out on its own, he's exhibiting a practice called barbering. He might do this for physical reasons such as parasites, disease, bacterial infections or skin irritants in his environment. The hair-pulling is a relief for your pet's pain, itching or other discomfort. He also could do it for psychological reasons such as feeling unsafe in his enclosure or being dominated by another hamster. Once again, a vet's intervention will help you determine the cause and treatment.
Syrian hamsters have scent glands on their hips that can look like lumps or cuts. These are actually normal and not likely to cause any health issues. However, if he licks them or rubs them against his cage or wheel to mark his territory, the hair around the glands could start wearing thin. This practice is called overscenting. To remove his need to keep marking, try leaving some of his old bedding and nest material behind each time you clean his cage and leave his scent on his wheel and other toys.
Dwarf male hamsters have scent glands on their bellies that are usually stained a yellow color. Their location makes the glands easy to become infected through overscenting or getting litter stuck to them. Check his scent glands regularly and gently wipe off any crusty-looking secretions with a cotton swab. If the area is red, raised or covered in pus, it's infected and you need to see a vet right away.
If your hamster is losing hair when the weather warms up, it could be just seasonal shedding. Some hamsters also begin to shed more as they get older or if they're petted or groomed too much.
Hamsters are great at grooming themselves, so you don't need to brush or comb their fur.
Hamsters love to be petted and it helps them bond to you, but it's possible to give too much of a good thing, so if you notice excess shedding try holding your hamster without constantly petting him.