* Brindle is a coat pattern, not a breed: Brindle is a specific coat pattern characterized by streaks or stripes of different colors. It's not a breed characteristic.
* Highland Terriers are always white: Highland Terriers are known for their distinctive white coats. They are not known to carry genes for brindle patterns.
* Jack Russell Terriers can have brindle: While Jack Russell Terriers can come in various colors, including brindle, a white Highland Terrier parent would not pass on the brindle gene.
Possible Explanations:
* Misidentification: It's possible there might be a mistake in identifying the puppy's father. It could be that the father is a different breed that carries the brindle gene.
* Genetic Testing: If you're curious about the puppy's genetics, consider a DNA test. This can confirm the breed of the puppy's parents and reveal any genetic predispositions.
In short, the puppy's brindle coat pattern is likely due to the Jack Russell Terrier mother, but the white Highland Terrier father couldn't contribute to the brindle coloration.