Do dogs harbour risk factors for human breast cancer?
We ask consulting patients regularly whether they keep pets in order to identify zoonotic factors. It became apparent that patients with breast carcinoma (N=69) owned significantly more often dogs but not cats compared to age matched female controls. We compared the frequencies of dog and pet ownership with data from public available statistics on women (N=1320) of the same age group in Bavaria. The most striking result was that more than twice the number of patients kept dogs permanently in the last 10 years and at the time of interrogation as compared to control individuals at the time of interrogation (p=0.0000003, relative risk 3.5). Further internet search on the morbidity of breast carcinoma showed in dogs a protracted course of disease and metastases into lung, liver and bones, resembling the course of disease in human breast cancer. In contrast with this, breast cancer presented in cats a dramatically short course and the main but unusual location of metastasis presents in the
