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.