Sometimes we see dogs with short coats who have mostly long-haired dogs in their ancestry. This can certainly be surprising for pet parents!
In most dogs, coat length is controlled by a single gene, called FGF5. Long hair is a recessive trait, which means that the variant of FGF5 coding for a long coat needs to be inherited from both parents.
What does this mean for your dog? Even if a dog has mostly long-haired breeds in their ancestry, they will still have a short coat even if only one parent conferred the short-haired variant to them. Your dog may even carry for a long coat without expressing it. On our Trait results, this would look like a result of GT at the gene FGF5, where T is for a long coat and G is for the dominant short coat.