The purpose of the project was to see if there are differences in genetic variation among The Seeing Eye's breeds—golden retrievers (GR), German shepherds (GS), and Labrador retrievers (LR)—and to study whether differences in genetic variation are associated with selection response in the trainability score. Earlier studies indicated that the selection response in the trainability score was lowest in the GR population, which was the smallest of the 3 breeding populations at The Seeing Eye. Eighty blood samples from each of the 3 breeds at The Seeing Eye were analyzed for genetic variation using a battery of 20 microsatellites. The overall number of alleles varied from 7 to 16 for the microsatellites, and the overall heterozygosity was around 0.6. The average estimated within-breed heterozygosity was relatively similar in the analyzed LR and GR dogs, but it was significantly lower in the selected GS dogs. The studies of general genetic variation in these breeding populations did not support that the reason for a lower selection response in the GR was a result of low genetic variation. The study shows that surveillance of genetic variation in working dogs can add important information that can support breeding programs. When breeding for quantitative traits in dogs, it may be advantageous to survey genetic variation periodically to be sure that the level of genetic variation is not reduced.