Mouse parvovirus (MPV) infection is difficult to address because it is asymptomatic, persists for as long as 9 wk, and occurs in small subpopulations of mice. The efficacy of a PCR-based cage swabbing strategy for MPV detection was tested. On postinoculation days (PID) 3 through 63, feces were collected from MPV-infected SW mice or the wire bars and cage wall above and below the bedding were swabbed. MPV DNA was detected in all cages in all locations on PID 7 and 14 but only below the bedding on PID 21. Swabbing below the bedding detected MPV in most cages through PID 42. Sentinels exposed to soiled cages on PID 7 and 14 but not on PID 21 seroconverted. MPV was detected in feces from all cages until PID 33 and in at least 1 cage until PID 56. In BALB/c mice, MPV was detected in feces and on cage swabs on PID 5 to 14, and 80% of sentinels exposed to soiled cages on PID 7 and 14 seroconverted. In comparison, MPV infection of C57BL/6 mice was detected in feces on PID 5 to 14 and on swabs on PID 5 and 7, and 30% of sentinels exposed to soiled cages on PID 7 and 14 seroconverted. Swabbing of multiple cages in rows in which only 1 cage contained MPV-infected mice was ineffective. In conclusion, swabbing of individual cages can be used in a genotype-dependent manner as an adjunct to soiled bedding sentinels during the first 2 wk of infection.