Abstract
Brazil has two dog breeds recognized by the Fédération Cynologique Internationale: the Brazilian Terrier and the Brazilian Mastiff. The Brazilian Terrier is believed to descend from Jack Russell Terriers crossed with local strays and possibly Pinschers, while the Brazilian Mastiff is thought to have originated from crosses involving English Mastiffs, Bloodhounds, and English Bulldogs. Here, we partially sequenced the genomes of one pedigree-certified individual from each breed using Illumina HiSeq. We assembled and annotated their complete mitochondrial genomes and performed comparative phylogenomic analyses. The Brazilian Terrier showed the highest mitogenomic similarity to the Australian Shepherd, Miniature Dachshund, Rottweiler, Cairn Terrier, and Shetland Sheepdog. For the Brazilian Mastiff, the closest matches included the Schipperke, Walker Hound, Tibetan Spaniel, Bolognese, and Great Pyrenees. Analysis of the mitochondrial D-loop region confirmed these results with minor variations. Additionally, we analyzed a partial sequence of the MLPH gene in the Brazilian Terrier to document genetic variants associated with coat color dilution. Altogether, our findings indicate that the genetic origins of both Brazilian breeds are more complex than traditionally assumed. Future studies with broader sampling and nuclear sequencing will be essential to deepen our understanding of their ancestry and evolutionary relationships.