Recently an aggregated data meta-analysis showed that serum alkaline phosphatase (SALP) and proximal humerus location are predictors for shorter survival in canine osteosarcoma. To identify additional prognostic factors of mortality and metastasis an individual patient data meta-analysis (IPDMA) was conducted. Individual patient data from 20 studies, identified via the VSSO society, were pooled. Univariable and multivariable hazard ratios (HR) for metastasis and mortality were assessed, using stratified Cox models. The study included 1405 dogs who received surgical treatment, of which the metastasis status was measured in 1155 dogs and mortality status in 1336 dogs; median survival was 256 days. High versus normal SALP and weight (kg) were associated with an increase in hazard of metastasis [HR 1.34 (95%CI 1.07; 1.68) and HR 1.02 (per kg increase) (95%CI 1.01; 1.03)] and for mortality [HR 1.43 (95%CI 1.16; 1.77) and HR 1.02 (95%CI 1.01; 1.02)]. Distal radius tumor was associated with a lower hazard of metastasis compared to other locations: HR 0.75 (95%CI 0.58; 0.96). Proximal humerus and distal femur or proximal tibia location were related with an increased mortality: HR 1.53 (95%CI 1.26; 1.84) and HR 1.23 (95%CI 1.01; 1.49) compared to other locations. Older age (years) was associated with a higher hazard for mortality [HR 1.06 per year (95%CI 1.03; 1.09)] but not for metastasis: HR 1.03 (95%CI 0.99; 1.06). These results confirm findings from a recent aggregated data meta-analysis and (in addition) showed that tumor location, SALP, weight were prognostic factors for both mortality and metastasis. Age was a prognostic factor for mortality but not for metastasis. © 2013 Elsevier B.V.