Retrovirus-like particles associated with myeloproliferative disease in the dog

A case of granulocytic myeloproliferative disease with hypercalcaemia of malignancy in a 6-year-old Golden Retriever dog is described. Numerous retrovirus-like budding particles were observed at the cell surface of the neoplastic granulocytes, suggesting the presence of a new oncogenic virus. Several attempts by other workers to demonstrate the presence of an oncogenic retrovirus in canine lymphosarcoma have produced minimal results. This study suggests that non-lymphoid canine myeloproliferative disorders warrant further investigation.