It has been established that non-random chromosome aberrations are characteristic of specific types of many different human cancers. The knowledge of such aberrations has identified areas of the human genome to be targeted for further research. In the dog the extent and identity of chromosome aberrations associated with specific cancers is still largely unknown. In certain breeds, such as the Flat-Coated Retriever and Bernese Mountain Dog, soft tissue sarcomas account for up to 50 percent of all malignant tumors and thus represent a serious health and welfare issue for those breeds. These tumors are difficult to classify by conventional means and so attention is required to develop alternative approaches. Human soft tissue sarcomas have been demonstrated to be associated with specific chromosomal aberrations that have been shown to have both diagnostic and prognostic significance. This proposal will make use of major recent advances in canine molecular cytogenetics to identify recurrent chromosome aberrations associated with canine soft tissue sarcomas, in particular those of histiocytic origin. This project will identify areas of the canine genome associated with such cancers for further investigation at the sub-chromosomal level.