Hamsters over 1-year old may develop cysts in internal organs, particularly the liver. It is thought that these are due to defects in the development of ductal structures. The cysts contain a clear fluid and are lined by flattened epithelial cells. They do not produce clinical symptoms and are usually an incidental finding during post-mortem examinations. They do not require any treatment.
Ninety percent of elderly hamsters develop systemic amyloidosis, involving the kidneys in particular, which progresses more rapidly in females. Renal amyloidosis causes polyuria/polydipsia, oedema, ascites and proteinuria.
About three-quarters of elderly hamsters suffer from cardiac thrombosis, usually in the right atrium. The possible causes include degenerative cardiomyopathy, cardiac amyloidosis and septicaemia. The clinical signs are cyanosis, dyspnoea and sudden death. X-rays can demonstrate pulmonary oedema and enlargement of the cardiac shadow. The treatment consists of administering furosemide and digitalis at doses used in the cat. In emergencies, the treatment indicated is administration of oxygen and diuretics to stabilise the patient, before carrying out the radiological examination.
The incidence of spontaneous tumours in elderly hamsters is extremely high (up to 100%). The reported benign tumours include intestinal polyps, adrenocortical polyps, thyroid adenomas, papillomas of the stomach, haemangiomas of the spleen. The malignant tumours include lymphomas, leukaemias, intestinal adenocarcinomas and melanomas.