Given the economic importance of both clinical and subclinical mastitis, early detection of mastitis is one of the most exciting Precision Dairy Farming applications. Early detection of mastitis may increase the likelihood of bacteriological cure; thus, the economic losses associated with a case of mastitis may be reduced. Reductions in the duration of pain associated with mastitis may also improve animal well-being. Potential also exists to separate abnormal milk automatically. These tools may also help reduce the likelihood of transmission of mastitis between cows and prevent the infection from becoming chronic. Mastitis changes the concentration of anions and cations in milk. Adoption of electrical conductivity systems has been limited because of sensitivity and specificity limitations; however, new algorithms and quarter based measurement systems hold potential for improved results. Thermography and milk temperature have also been proposed; however, both tools are limited because not all causes of mastitis result in a temperature response. Color variation (red, blue, and green) sensors have been included in some automatic milking systems to detect blood in milk and color pattern changes in infected quarters. In-line sensors that essentially automate the California Mastitis Test or Wisconsin mastitis test have been commercialized. These systems could provide valuable herd management information for identifying cows contributing to changes in bulk tank SCC. Image analysis may potentially differentiate between changes in the physical content in milk (i.e., flakes and clots) and other foreign materials (i.e., bedding and manure particles (Brandt et al., 2010). Spectroscopy (visible, near-infrared, mid-infrared, or radio frequency) has been applied in commercial sensors systems to identify changes in milk constituents including SCC and mastitis-causing pathogens. Biosensors designed to detect a specific biological component of milk may also be used for mastitis detection. For example, the enzyme, L-Lactate dehydrogenase (LDH), is released because of the immune response and changes in cellular membrane chemistry and has recently been commercialized as a mastitis detection tool.