Evaluation of plasma kynurenine 3-monooxygenase and Ki-67 as screening biomarkers for neoplasia in dogs - Research study

Q: What was the main objective of evaluating KMO and Ki-67 in this study?

To compare plasma KMO activity and Ki-67 concentration between healthy dogs and dogs with neoplasms, and to assess their diagnostic efficacy.

Q: How many dogs were included, and how were control dogs defined?

A total of 162 dogs with different tumor types were included. Forty-six tumor-free dogs formed the control group.

Q: What did the results show about KMO and Ki-67 levels in dogs with neoplasia?

KMO expression was significantly higher in dogs with neoplasms than in tumor-free controls, and Ki-67 values were also higher in the neoplasia group. Diagnostic performance differed by ROC analysis.

Sep 22, 2026

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Early detection of tumors may improve outcomes in dogs, yet practical veterinary screening biomarkers remain limited. This case–control study compares plasma kynurenine 3-monooxygenase (KMO) activity and Ki-67 concentration between healthy controls and 162 dogs with diverse neoplasms. KMO expression and Ki-67 values were higher in neoplasia, showing diagnostic performance differences by ROC analysis. Results also indicate inconsistent biomarker concordance, while overall findings support KMO as an effective marker and Ki-67 as an adjunct.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages7

Reading Time18 min

AccessFree to download

Abstract

Background

Hypothesis/Objectives

Animals

Methods

Results

Conclusions and clinical importance

Introduction

Challenges in early canine cancer detection

Rationale for KMO and Ki-67

KMO in tryptophan pathway and immune modulation

Ki-67 as a proliferation marker

Journal of Veterinary Internal Medicine, 2026, 40(4), aalag145 [https://doi.org/10.1093/jvimsj/aalag145](https://doi.org/10.1093/jvimsj/aalag145) Original Research Small Animal Internal Medicine Oncology | Evaluation of plasma kynurenine 3-monooxygenase and Ki-67 as screening biomarkers for neoplasia in dogs
Ka-Mei Sio† , Chiao-Hsu Ke† , Chen-Si Lin* | | | --- | --- | | Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei 10617, Taiwan
*Corresponding author: Chen-Si Lin, Department of Veterinary Medicine, National Taiwan University, No. 1 Sec. 4 Roosevelt Rd., Taipei 10617, Taiwan, ROC ([cslin100@ntu.edu.tw](cslin100@ntu.edu.tw)) .
† Ka-Mei Sio and Chiao-Hsu Ke contributed equally as first authors.
Abstract
Background: Early detection of tumors might prolong the survival of dogs. Kynurenine 3-monooxygenase (KMO) and Ki-67 are tumor biomarkers, but few studies have described the clinical value of KMO and Ki-67 in veterinary medicine.
Hypothesis/Objectives: This study aims to compare the activity of KMO and the concentration of Ki-67 between healthy dogs and dogs with neoplasms.
Animals: A total of 162 dogs with different types of tumors were included. Forty-six tumor-free individuals were included asthe control group.
Methods: This is a case–control study. Dogs with neoplasms, confirmed through medical record review, were recruited. The primary outcomes were the plasma concentrations of KMO and Ki-67, along with their diagnostic efficacy.
Results: Expression levels ofKMO were significantly higher in dogs with neoplasms (median, 2.02 ng/mL; IQR, 1.03-3.65) than in tumor-free individuals (median, 0.69 ng/mL; IQR, 0.23-1.18; P < .0001). The values of Ki-67 were higher in dogs with neoplasms (median, 4.28 ng/mL; IQR, 3.75-4.84) than in the control group (median, 3.80 ng/mL; IQR, 3.31-4.43; P < .05). No significant correlation was found between KMO and Ki-67 concentrations (R2 = 0.003, P = .48) in the tested samples and 50.6%(82/162) of dogs exhibited inconsistent results. The area under the ROC curve for KMO and Ki-67 were 0.837 and 0.644.
Conclusions and clinical importance: This study presents that KMO is an effective biomarker and Ki-67 is an adjunctive marker.
While lacking standalone diagnostic utility, Ki-67 reflects systemic tumor biology and complements biomarkers such as KMO. Keywords Ki-67, kynurenine 3-monooxygenase (KMO), liquid biopsy, tumor biomarker
Abbreviations AFP, alpha-fetoprotein; AUC, area under the curve; CEA, carcinoembryonic antigen; EDTA, ethylenediaminetetraacetic acid; HRP, horseradish peroxidase; KMO, kynurenine 3-monooxygenase; LDH, lactate dehydrogenase; NSAIDs, non-steroidal anti-inflammatory drugs; PSA, prostate-specific antigen; SAA, serum amyloid A; TMB, tetramethylbenzidine | | | Introduction
Cancer is a major cause of illness and death in dogs, with early and accurate diagnosis remaining challenging in veterinary medicine.1 , 2 Traditional methods, such as histopathology and imaging, are invasive, expensive, and time-consuming, restricting their use for routine screening. In human medicine, blood biomarkers such as alpha-fetoprotein,3 carcinoembryonic antigen,4 prostate-specific antigen,5 , 6 and cancer antigens (CA-125, CA19-9) are widely used for cancer detection and monitoring.7 , 8 In veterinary medicine, research on blood biomarkers is increasing, and biomarkers such as serum amyloid A,9 , 10 lactate dehydrogenase (LDH),11 and Ki-67 show promise for tumor detection | and prognosis.12 , 13 However, single markers often lack sufficient sensitivity and specificity. Combining multiple biomarkers might improve diagnostic accuracy.14 , 15 Identifying reliable biomarkers that simultaneously reflect diverse aspects of tumor biology could enhance the early detection and management of cancer in dogs. These strategies have been developed in human oncology and also offer new tools for veterinary medicine.2<

FAQs

What was the main objective of evaluating KMO and Ki-67 in this study?

To compare plasma KMO activity and Ki-67 concentration between healthy dogs and dogs with neoplasms, and to assess their diagnostic efficacy.

How many dogs were included, and how were control dogs defined?

A total of 162 dogs with different tumor types were included. Forty-six tumor-free dogs formed the control group.

What did the results show about KMO and Ki-67 levels in dogs with neoplasia?

KMO expression was significantly higher in dogs with neoplasms than in tumor-free controls, and Ki-67 values were also higher in the neoplasia group. Diagnostic performance differed by ROC analysis.

Sep 22, 2026

Upload by Evangeline