Investigation of the Intensity of Thrombocytosis as a Potential Prognostic Indicator in Canine Malignant Neoplasms

Platelets contribute to cancer progression, and thrombocytosis is a recognized poor prognostic factor in human oncology; however, its significance in veterinary medicine remains underexplored. We retrospectively analyzed 166 dogs diagnosed with neoplasia and thrombocytosis (platelet count ≥ 430,000/μL) to assess the relationship between thrombocytosis intensity and survival. Survival analyses revealed that compared with dogs with mild thrombocytosis, those with moderate‐to‐severe thrombocytosis had significantly shorter survival times. With respect to specific diagnoses, dogs with mammary carcinoma and moderate‐to‐severe thrombocytosis had a significantly higher risk of death (HR = 3.4; p = 0.02). A similar trend was observed in patients with mast cell tumors, where the risk of death was 7.39 times higher, although this finding reached only borderline statistical significance ( p = 0.05). Further prospective studies with larger cohorts are warranted to validate thrombocytosis as a prognostic biomarker and to elucidate its role in tumor biology and clinical outcomes in veterinary oncology.