Hamsters moult throughout the summer and autumn and at this time many hamsters may have periods where their coats are sparse or may have areas of fur loss. During times of sudden and extreme temperature changes fur loss resulting in large bald patches can also occur. This is usually nothing to be concerned about and the hamster's fur will usually start to regrow within a few weeks. All species of hamsters moult but the Chinese and Roborovski hamsters are generally less affected than the Russian species and the Syrian Hamster.
Nursing female hamsters may often develop some fur loss on their stomach and this is usually nothing to be concerned about as the fur will regrow once nursing is complete.
Fur loss can also occur in older hamsters (usually around one year of age or over) and usually occurs on the belly, hind legs and hip areas first.
If fur loss is observed the skin of hamster should first be checked for any signs of irritation, flakiness, scabs or sores. The hamster should also be observed for excessive scratching or any other signs of illness ie weight loss, lethargy, etc. If the hamster is exhibiting any signs of illness along with fur loss the hamster should be isolated from any others and veterinary advice sought immediately.
General fur loss due to old age or moulting (with no other symptoms) can be helped by crushing a yeast tablet on the hamster's food every other day, lessening the amount once the fur has started to regrow. (Yeast tablets can usually be found at a chemist or pharmacy amongst the human vitamin tablets). If yeast tablets are unavailable, vitamin drops (available from pet stores) added to the water will aid fur re-growth.