Serum thymidine kinase activity in clinically healthy and diseased horses: a potential marker for lymphoma.

Abstract Serum thymidine kinase (sTK) activity is a tumour marker used as a prognostic indicator for lymphoma in humans, dogs and cats. The aim of this study was to evaluate the clinical utility of sTK as a biomarker for lymphoma in horses. Serum samples were collected from clinically normal horses ( n  = 37), horses with lymphoma ( n  = 23), horses with non-haematopoietic neoplasia ( n  = 9) and horses with inflammatory disease ( n  = 14). sTK was measured using a radioenzyme assay. A reference cut-off value of  P  0.01), horses with inflammatory disease ( P  0.01) and horses with non-haematopoietic neoplasia ( P  0.05). sTK activity is a potentially useful biomarker for equine lymphoma.