It is possible to keep hamsters of one sex from the same litter together but generally they are best kept as individuals to avoid fighting. Males reach sexual maturity at 6-8 weeks and females at 4 weeks, though the latter tend not accept a mate until 8-12 weeks. If you wish to breed from your hamsters, care must be taken as the female will attack the male unless she is 'in heat', so supervision is essential. The female must be taken to the male or the pair should be brought together in neutral territory, with the female being removed as soon as mating has occurred (usually the early evening).
Hamsters differ from other rodents in having a well-defined fore stomach which enables them to digest protein and carbohydrate more effectively, but also increases their requirements for certain vitamins and minerals. Most pelleted diets are satisfactory, providing they are fresh, but it is a good idea to supplement them with seeds, grains, fruit and green vegetables to add variety. Fresh, clean water should always be available.
The most common medical conditions seen in hamsters are intestinal disorders, such as 'wet tail'. Diarrhoea is often serious and can be life-threatening, so needs prompt attention and treatment.
As with guinea pigs and rabbits, a hamster's teeth will grow continuously and it is important to check that they wear normally. If malocclusions occur (where the teeth do not meet properly, so wear unevenly), they have to be corrected by regular clipping or burring. Dental problems may result in facial abscesses but a more likely cause of swelling of the face is impaction of the cheek pouches with stored food (which can become adherent to the dry inner surface of the mouth in this region). If this happens, the pouches should be gently emptied and flushed with water.
Hamsters are prone to various forms of pneumonia caused by viral, bacterial or mycoplasmal agents, or a combination of the three. Respiratory disease is usually acute in onset and is characterised by oculonasal discharge, inappetance and breathing difficulties. Affected hamsters should be kept in a warm and stress-free environment and veterinary attention should be sought as soon as possible.
Most skin problems in hamsters are due to mite infestations, although ringworm can occasionally occur. Treatment is available from your vet. Bilateral alopecia in older animals may be glandular in origin, rather than due to parasites, and treatment may not be necessary if the hamster is otherwise well.