Learn how infrared thermography and LED photodynamic therapy can detect and treat bovine mastitis early—non-invasive, effective, and antibiotic-free.
Mastitis remains one of the dairy industry’s biggest challenges; it is the most common and costliest disease in dairy animals and causes major economic losses. Sub-clinical mastitis (SCM) is especially worrisome because it occurs more often than clinical cases. On most farms, both SCM and clinical mastitis (CM) are tracked with indirect tests—pH, electrical conductivity, somatic cell count (SCC), California mastitis test (CMT), culture, and selected biomarkers.
Even so, faster, more sensitive tools are needed to spot udder infections early. Non-invasive methods that detect mastitis sooner could help limit losses for the industry and for individual farmers. Skin temperature rises when inflammation, local blood flow, and metabolism increase, so monitoring heat emitted from the udder may allow earlier detection. Infrared thermography (IRT) with a sensitive thermal camera can pick up these small temperature changes, and a mobile-based IRT app could support day-to-day herd management.
In 1800, British astronomer Sir William Herschel discovered infrared (IR) radiation in sunlight. IR electromagnetic wavelengths span 700 nm (430 THz) to 1 mm (300 GHz). IRT relies on the Stefan–Boltzmann law: every object emits IR radiation in proportion to its temperature. By imaging this radiation, IRT reveals subtle surface-temperature shifts linked to changes in blood flow.
Healthy udders are essential for clean milk. Good milking practices lower infection risk and support milk quality. Researchers now use IRT to monitor the milking process; udder thermograms can also reflect milking hygiene because dirt on the teat skin alters surface-temperature readings. The main threat to udder health is mastitis—an inflammation that triggers physiological, biochemical, and pathological changes in udder tissue and alters milk composition.
IRT can detect both clinical and sub-clinical mastitis. Sub-clinical disease is the larger economic burden, often lowering milk yield and quality permanently. Early IRT screening may identify cases sooner, guide treatment, and help limit losses. Studies report that IRT sensitivity and specificity for sub-clinical mastitis are comparable to those of the California mastitis test. A temperature rise of more than 1 °C in the udder may signal mastitis, suggesting IRT can serve as a complementary screening tool in Holstein and Brown Swiss cows.
Fig 1: Infrared thermogram of udder quarters (lateral view). RFQ: right front quarter; RHQ: right hind quarter; LFQ: left front quarter; LHQ: left hind quarter.
PubMed search for mastitis thermography | FDA animal health resources | WHO food-safety topics
Changes in udder surface temperature, measured by infrared thermography (IRT), differ between healthy quarters and those with sub-clinical or clinical mastitis. Although reported temperature ranges vary, IRT remains a promising, non-invasive screening tool; however, results for sub-clinical cases are inconsistent, while clinical mastitis is usually detected more reliably.
Methods: Forty cows with sub-clinical mastitis (n = 40) were assigned to four groups: control, photodynamic therapy (PDT), light irradiation (LED), or photosensitizer (PS) only. The control group received no treatment. The PDT group received 1.0 mL of 2.5 % toluidine blue followed by LED irradiation (λ = 635 nm). The LED group was irradiated without dye, and the PS group received dye alone. Light (200 J/cm²) was delivered at three sites within the gland via an acrylic light guide. Milk samples were collected at 0 h, 12 h, and 24 h for microbial identification and total bacterial count.
Results: PDT produced a significant reduction (p < 0.05) in Streptococcus dysgalactiae and coagulase-negative Staphylococcus compared with the other groups.
Conclusion: In this study, photodynamic therapy reduced bacterial load in sub-clinical bovine mastitis without requiring withdrawal from milking.
Mastitis causes major economic losses in dairy farming. While standard laboratory tests remain the reference, non-invasive methods such as infrared thermography could support earlier detection. Thermal cameras can pick up subtle udder-temperature changes associated with inflammation, but sunlight, moisture, dirt, and ambient temperature may influence readings. Further work under varied field conditions is needed before IRT can be recommended as a stand-alone diagnostic.
Further reading:
Bangar, Y. C., Singh, B., Dohare, A. K. and Verma, M. R. (2015). A systematic review and meta-analysis of the prevalence of subclinical mastitis in dairy cows in India. Trop Anim Health Prod., 47: 291–297.
