Tumours and Cancers usually occur in older hamsters and are more common in females than in males.

Internal tumours such as those involving internal organs may be difficult to treat but many external tumours can be successfully surgically removed.

A hamster suffering from cancer may develop a hard lump which can increase in size quite quickly. It is often difficult to distinguish between a tumour and an abscess. A tumour may be accompanied by fur loss, lethargy, poor condition or wasting but not always. On discovery of any lump veterinary advice should be sought immediately as early diagnosis increases the chances of success of surgical removal of tumours.

Because of their small size there is a risk from the anaesthetic required to carry out surgery but many elderly hamsters have successfully undergone surgery of this kind.