Jönköping Small Animal Hospital is today the only clinic in Sweden to offer radiation therapy as a treatment of tumours. The body contains of billions of cells that all have to obey the regulations that are established. If a cell is exposed to a harmful substance, for example a chemical, it can be transformed into a tumourcell. Normally the body has a good defence but the tumourcell can survive and start to divide unrestrained. A tumour is starting to develop.