In veterinary medicine, serum TK1 has also been evaluated as a biomarker for diagnosis and prognosis, primarily in dogs with haematopoietic malignancies [12–14] but also in horses with lymphoma, with a sensitivity of 74% and a specificity of 86% and an AUC (are under the curve) of 0.80 as a diagnostic biomarker for this disease [15]. This evidence concerns the gene TK1 and lymphoma.