Measurement of the cell loss from two spontaneous canine tumours.

Estimates of the cell loss from spontaneously occurring tumours in two dogs were made by the intranuclear isotope-labelling technique. The dogs were injected with 125iodine labelled iododeoxyuridine and tumour biopsies taken at intervals so that the potential doubling time of the tumours and the cell loss factor could be estimated from the radioactive content per unit weight. This is the first report of the use of this method with spontaneously occurring tumours in dogs. Cell loss factors of over 90 per cent were recorded in each case, correlating well with information obtained from other techniques for spontaneous human and canine tumours.