In dogs, white spotting is of interest because in some cases of extreme white spotting, in which a dog is nearly entirely white, dogs may also have health disorders including blindness and deafness. Nine candidate genes were tested for association with spotting in dogs, including SOX-10, MCOLN3, EDN3, KITLG, PAX3, MITF, ASIP, ADAMTS20, and SNAI1. These genes were either ruled out (SOX-10, MCOLN3, EDN3, KITLG, PAX3), were not useful in the families in this study (ASIP, ADAMTS20, SNAI1), or studied further (MITF). A genetic mutation called a single nucleotide polymorphism (SNP) in the microphthalmiaassociated transcription factor gene (MITF) was discovered and genetic tests were designed to classify the dogs (Beagle crosses and Newfoundlands) into their different genotypes (the combination of alleles located on paired chromosomes that determines a specific characteristic or trait). Studies showed an association between the genotypes and the observed white spotting in the dogs’ coat color. Results suggest that MITF may predict spotting in these breeds.