Table 1.

Different Diagnostic Tools Used to Detect Subclinical Mastitis

Diagnostic Tool	Description	Reference
Physiochemical diagnostics Electrical conductivity pH Biochemicals	Milk conductivity, pH, and Biochemicals including lactose, amyloid A, peptides, and enzymes [such as N-acetyl-β-d-glucosaminidase, LDH, ALP] have the potential to be used as a marker for subclinical mastitis.	[155,185–189]
Somatic cell count (SCC)	SCC has larger accuracy with sensitivity, specificity of 94.9%- 99.5%, and 48.1%-87.1%. It is expensive and done in laboratories with DeLaval cell counter, Fossomatic cell counter, Portacheck	[190,191]
California mastitis test	CMT is a simple, quick, and cost-effective approach with lower accuracy (87.4–90.8%), sensitivity, and specificity than other tests.	[192]
Automatic digital diagnostics	Automated milk leucocyte differential test (MLD) (Qscout)	[193]
Immunochromatographic strips	The development of a nanoparticle-based–coated immunochromatographic strip (ICS) that accurately identifies mastitis-causing bacteria helps in successful management by both dairy farmers and veterinarians and can be utilized to implement the selective use of antimicrobials for therapy.	[194,195]
Infra-red thermography	IRT is a simple, convenient, and portable diagnostic technique for diagnosing subclinical mastitis.	[196,197]
Sensor-based mastitis detection systems	The proteolytic activity of plasmin as a biomarker was used to develop a magnetic nanoparticles-based colorimetric biosensor assay that was sensitive enough to detect modest levels (1ng/mL) of plasmin present in vitro in milk samples.	[163,198]
Proteomic approach	Many proteins are being investigated for their diagnostic potential in proteomics-based disease diagnosis.	[199,200]
Specific culture	Accumast, Minnesota Easy system, Staphylococcus, Streptococcus, Gram-negative (SSGN), Staphylococcus, Streptococcus, Gram-negative chromogenic quad plate (SSGNC), Petrifilm system	[201,202]
PCR and its versions	PCR techniques for pathogen detection in mastitic milk samples with sensitivity of 76.9–100% and specificity of 63.3–98.7%.	[203,204]
MALDI-TOF	Modern phenotypic testing is based on proteomics and can be applied directly to milk samples using MALDI-TOF spectrometric analysis.	[205,206]
ELISA	ELISA could make the diagnosis of mastitis through new biomarkers.	[188,207]