The American Bulldog breed has gained popularity as both a companion and guard dog, increasing demand for animals with desirable aesthetic traits, health, and stable temperament. While brindle coloration remains predominant, it is often less valued by the market. Diluted coat colors, such as blue and fawn, are rare but highly valued. This study aimed to increase the frequency of the dilution allele (dd) in the American Bulldog breed through backcrossing with Olde English Bulldogge. The study was conducted at Sunshine Land Kennel. A blue coat Olde English Bulldogge male was bred with a chocolate coat American Bulldog female. From 10 offspring, 8 expressed the diluted phenotype, including 4 blue and 4 Isabella individuals. The results demonstrate the effectiveness of controlled genetic selection strategies in increasing allele frequency while maintaining breed standards. This work contributes to the understanding of coat color genetics and applied breeding strategies in canines, with practical implications for breeders and genetic selection programs.

Este estudo teve como objetivo aumentar a frequência do alelo diluidor (dd) na raça Bulldog Americano por meio de retrocruzamento com a raça Olde English Bulldogge. O experimento foi conduzido no Canil Sunshine Land e demonstrou a eficácia da seleção genética controlada na obtenção de fenótipos diluídos, mantendo o padrão racial. Os resultados contribuem para a compreensão da genética de pelagem e sua aplicação prática em programas de melhoramento genético canino.