Diagnostic records are a key feature of any cancer epidemiology, prevention or control strategy for both human beings and animals. Thus, the information stored in human and animal cancer registries is essential to comparative epidemiologic, pathogenic and therapeutic research. This study presents the Swiss Canine Cancer Registry, compiled between 1955 and 2008. The data consists of pathology diagnostic records issued by three veterinary diagnostic laboratories in Switzerland. The tumours are classified according to the International Classification of Oncology for Humans (ICD-O-3) guidelines: tumour type, malignancy and body location (WHO, 2013). The dogs are classified according to breed, age, sex, castration status and place of residence. The diagnostic data were correlated to the relative dog population and the occurrence of cancer in dogs was thus investigated. In 121,963 canine patients 67,943 tumours were diagnosed. 47.07% of which were malignant tumours. The most common tumour location was the skin (37.05%), followed by mammary glands (23.55%) and soft tissue (13.66%). The most common tumour diagnoses were epithelial (38.45%), mesenchymal (35.10%) and lymphatic tumours (13.23%). The results are compared with other canine registries. Similarities to tumour distribution and incidence in other findings are listed and specific difficulties in comparison are pointed out. We hope that this study will mark the beginning of a continuous registration of dog tumours in Switzerland, which, in turn, will serve as a reference for research in the fields of animal and human oncology. The diagnostic data were correlated to the relative dog population and the 25 occurrence of cancer in dogs was thus investigated. In 121,963 canine patients 26 67,943 tumours were diagnosed. 47.07% of which were malignant tumours. The 27 most common tumour location was the skin (37.05%), followed by mammary glands 28 (23.55%) and soft tissue (13.66%). The most common tumour diagnoses were 29 epithelial (38.45%), mesenchymal (35.10%) and lymphatic tumours (13.23%). 30The results are compared with other canine registries. Similarities to tumour 31 distribution and incidence in other findings are listed and specific difficulties in 32 comparison are pointed out. We hope that this study will mark the beginning of a 33 continuous registration of dog tumours in Switzerland, which, in turn, will serve as a 34 reference for research in the fields of animal and human oncology. 35 36