# Functional Role and Diagnostic Potential of Biomarkers in the Early Detection of Mastitis in Dairy Cows

## TL;DR

This paper reviews new biomarkers for early detection of mastitis in dairy cows, aiming to improve diagnosis beyond the current gold standard.

## Contribution

The paper synthesizes recent research on novel biomarkers for early and accurate mastitis detection in dairy cows.

## Key findings

- Biomarkers like lactoferrin, β-defensin 4, and microRNAs show promise in detecting subclinical mastitis.
- Current biomarkers lack the specificity and reliability for routine farm use, suggesting the need for combined panels.
- MicroRNAs are highlighted as stable and sensitive indicators for intramammary inflammation.

## Abstract

Mastitis is one of the most common and costly diseases in dairy farming, with major impacts on cow welfare, milk quality, and farm productivity. Nowadays, somatic cell count can be still considered the gold standard indicator for diagnosis but lacks sensitivity for early or subclinical mastitis and cannot identify the pathogens involved. Therefore, recent study has been developed to identify biomarkers that could reveal subclinical mastitis and/or identify the pathogens involved. Several promising molecules, including lactoferrin, β-defensin 4, vitronectin, paraoxonase 1, N-acetyl-β-D-glucosaminidase, and microRNAs, have shown potential in detecting intramammary inflammation, with microRNAs emerging as particularly stable and sensitive indicators. Although these advances are encouraging, no single biomarker has yet to be accurate and reliable enough for routine use on farms, and future diagnostic strategies will likely rely on combined biomarker panels to improve early detection and mastitis management.

Mastitis remains a prevalent and economically detrimental disease within the dairy industry, profoundly affecting animal welfare, milk quality, and overall production output. Nowadays, Somatic Cell Count (SCC) is widely recognized as the gold-standard indicator for the detection of mastitis; however, its limitations in pathogens discrimination and the lack of early-stage characterization of mastitis highlight the need for complementary diagnostic approaches. This review synthesizes recent research into the development and validation of novel biomarkers for the early and accurate identification of mastitis in dairy cows. The investigation encompasses a range of biological molecules for improving mastitis diagnosis. Biomarkers such as lactoferrin (LTF), β-defensin 4 (DEFB4), vitronectin, paraoxonase 1 (PON1), and N-acetyl-β-D-glucosaminidase (NAGase) show promise in distinguishing between cows not susceptible and cows susceptible to mastitis. Concurrently, nucleic acid-based biomarkers are emerging as a particularly promising frontier. While mitochondrial DNA (mtDNA) has demonstrated insufficient specificity, microRNAs (miRNAs) are gaining attention as highly stable and sensitive indicators of intramammary inflammation, potentially enabling the detection of subclinical infections before they become clinically apparent. Despite these advances, significant challenges related to specificity, reliability, and cost-effectiveness currently hinder the widespread practical application of any single biomarker. Therefore, future research should be directed towards the validation of a synergistic panel of multiple biomarkers to improve mastitis management in dairy cow farms.