Diagnostic Specificity of Serum Carcinoembryonic Antigen for Canine Mammary Neoplasms: The Impact of Non-Neoplastic Diseases

Abstract Carcinoembryonic antigen (CEA) is a glycoprotein produced by normal mucosal cells of the gastrointestinal tract and has been utilized as a tumor biomarker in humans. In veterinary medicine, canine patients with mammary neoplasms present elevated CEA levels. However, CEA is also known to increase in other pathological conditions. This study compared serum CEA levels in dogs with mammary carcinoma and those with non-neoplastic diseases. Blood serum samples were collected from 118 dogs (101 females and 17 males) and were divided into five experimental groups: control (G1), mammary neoplasia (G2), ehrlichiosis (G3), gastroenteritis (G4), and non-neoplastic diseases (G5). CEA levels were measured using a human ELISA kit, and the results were analyzed and compared across the experimental groups. Statistical analyses included Tukey's test, ROC curve analysis, and Pearson’s correlation, with a significance level of 5%. The results demonstrated significant differences in mean CEA levels between groups G1 and G2 (P < 0.0001), G1 and G4 (P = 0.0267), and G1 and G5 (P = 0.0070), with elevated values in mammary carcinomas and non-neoplastic diseases. Greater sensitivity and specificity were noted in G2 compared to the other groups. However, specificity significantly dropped when non-neoplastic diseases were compared to mammary carcinomas. Furthermore, a moderate positive correlation was found between CEA levels and platelet count, indicating a possible influence of inflammation on the variation of this biomarker. The results demonstrated that CEA has good diagnostic value for dogs with mammary carcinomas; however, this was not observed for non-neoplastic diseases. However, non-neoplastic diseases can drastically affect CEA specificity. Future studies evaluating additional diseases will be necessary for a better understanding and clinical application of this biomarker in veterinary practice.