Body care (grooming) is a behavioral adaptation for removing litter particles, pathogenic microbes, and parasites from animal fur and skin. It also serves as an indicator of animal health. Here a technique of direct measurement of fur cleaning has been developed. A spot of fluorescent dye applied on the back of a mouse was scanned under blue light (450 nm) immediately and rescanned 1, 2, 4, 8, and 24 hours later with a digital camera. The spot fluorescence intensity was measured using ColorScan software, which we developed using a classifier algorithm. The decrease in the spot fluorescence served as an index of fur cleaning, with significant interstrain differences in the dynamics of fur cleaning: mice of C57BL/6, CBA, CC57BR, and DD strains removed the fluorescent spot rapidly (1-2 h) whereas AKR and DBA2 mice did so slowly (24 h). To study the association between fur cleaning and stress or sickness we investigated the effect of restriction stress (for 30 min) and of the bacterial toxin lipopolysaccharide (LPS) on fur cleaning in two fast-cleaning mouse strains, CBA and C57BL/6. Restriction substantially reduced fur cleaning in the CBA mice but had no effect on the C57BL/6 mice. LPS decreased fur cleaning in a dose-dependent manner in both strains. The described technique is fairly simple and sensitive enough to estimate the effects of both stress and LPS treatment. It can be applied to study vulnerability (or resistance) to stressors, pathogenic organisms, and toxic substances.