犬乳腺肿瘤是雌性犬最常见的肿瘤类型，严重威胁其生命。当前尚无有效的治疗方法可用于此疾病。因此，有必要鉴定对此病的早期诊断、治疗和预后产生积极影响的生物标志物。为了提供犬乳腺肿瘤的早期诊断依据，本研究通过组织病理学检查结合血液检查和诊断影像学的辅助诊断方法，确定了23只患有乳腺肿瘤的犬。收集了犬乳腺肿瘤和肿瘤旁健康组织，并利用基于UHPLC-qTOF-MS的无靶向代谢组学方法鉴定了它们的代谢物。代谢结果显示了两组组织中正极性模式下的979个离子特征和负极性模式下的371个离子特征；其中，通过PCA和PLS-DA分析了536个差异代谢物（正极性模式下的385个和负极性模式下的151个）。随后，利用Metaboanalyst 4.0分析了富集通路嘌呤代谢、α-亚麻酸代谢、维生素B6代谢和脂肪酸生物合成，表明这些通路是有价值的诊断和治疗靶点。此外，接收操作特征曲线进一步确认了13Z，16Z-二十二二烯酸、23-去氧胆酸和(±)12(13)-DiOME作为犬乳腺肿瘤预期候选生物标志物。总之，基于无靶向代谢组学的肿瘤标志物的发现对病理机制研究具有重要意义，并且有助于犬乳腺肿瘤的早期诊断。版权所有©2023 Elsevier公司发表。

The canine mammary tumor is the most common tumor type in female dogs and seriously threatens their life. Currently, no effective treatments are available for this condition. Hence, it is essential to identify biomarkers that positively influence the early diagnosis and treatment and prognosis of this disease. To provide a basis for early diagnosis of canine breast tumors, in this study, 23 dogs with mammary tumors were identified via histopathological examination combined with ancillary diagnoses via blood examinations and diagnostic imaging. The canine mammary tumor and tumor-adjacent healthy tissues were collected, and their metabolites were identified utilizing a UHPLC-qTOF-MS-based untargeted metabolomics approach. The metabolic results revealed a total of 979 ion features in the positive polarity mode and 371 ion features in the negative polarity mode in the tissues of two groups; among them, 536 differential metabolites (385 in the positive and 151 in the negative polarity mode) were analyzed by PCA and PLS-DA. Subsequently, the enrichment pathways purine metabolism, alpha-linolenic acid metabolism, vitamin B6 metabolism, and fatty acid biosynthesis were analyzed using Metaboanalyst 4.0, which suggested that these pathways were valuable diagnostic and therapeutic targets. Moreover, the receiver operating characteristic curves further confirmed 13Z,16Z-docosadienoic acid, 23-nordeoxycholic acid, and (±)12(13)-DiHOME as expected candidate biomarkers of canine mammary tumors. In conclusion, the discovery of tumor biomarkers based on untargeted metabolomics is informative for pathological mechanism studies and facilitates the early diagnosis of canine mammary tumors.Copyright © 2023. Published by Elsevier Inc.