Osteosarcoma (OS) is the most common type of malignant primary bone tumour in dogs and humans. In addition to their critical roles in bone formation and remodelling, parathyroid hormone-related protein (PTHrP) and its receptor (PTH1R) are involved in progression and metastasis of many types of tumours in humans. The aims of this study were to determine the localisation and expression levels of PTHrP and PTH1R in canine OS tissues using immunohistochemistry and to investigate if this expression is correlated with survival. Formalin-fixed, paraffin-embedded tissue samples from 51 dogs with known survival time that had been diagnosed with primary osteosarcoma were analysed for localisation of PTHrP and PTH1R. Findings showed that both PTHrP and PTH1R were present in all OS samples. The dogs with high level of PTH1R protein had decreased survival time (P<0.05) compared to dogs with less PTH1R protein. PTHrP levels did not correlate with survival time (P>0.05). The results of this study indicate that the PTH1R is expressed differently in canine OS tissues and this may be correlated with poor prognosis. This suggests PTH1R may be useful as a prognostic indicator in canine OS and could represent a good therapeutic target.