Oestrogen receptors in feline mammary carcinomas.

Twenty primary or metastatic felline mammary tumours were assayed for the presence of oestrogen receptors by the dextran-coated charcoal method. In only two of the tumours was the presence of specific oestrogen binding protein demonstrable. The high negative rate in comparison with human and canine mammary tumours assayed under similar conditions seemed to be a peculiar feature of the feline tumours and suggested a lack of oestrogen dependency. The possibility remains that other hormones may be concerned with the growth of feline mammary tumours and further work is in progress.