Dogs share with humans several zoonotic diseases as well as some important determinants of degenerative syndromes and tumours. For this reason, systematic surveillance on small animal disease carried out through the collection and analysis of necropsy records could be helpful to public health. To describe the causes of death in dogs from the province of Rome (Italy) submitted to the Istituto Zooprofilattico Sperimentale del Lazio e della Toscana for necropsy during 2003-2007, a retrospective study was conducted on diagnostic data of 870 dogs. The final diagnosis was established by anatomo-histopathological examinations and, when needed, by ancillary laboratory tests. The most common causes of death were 'infectious disease' (23%) and 'poisoning' (17%). In 5% of the cases, the cause remained undetermined. The frequency of 'poisoning' was higher (39%) in stray dogs, while 'infectious disease' was more frequent (49%) in dogs from breeding farms. Parvovirosis was the most frequent infectious disease (33%) while anticoagulants accounted for 30% of the cases involving toxicity. Death by neoplastic lesions was quite infrequent (7%). Findings from this study provide veterinarians with an overview of the causes of death in dogs and it could provide public health authorities with new data about both novel and re-emerging threats.