What do you call a Jack Russell x border terrier?

There isn't a specific, widely recognized name for a Jack Russell x Border Terrier mix.

However, you can describe the dog as:

* Jack Russell Terrier and Border Terrier mix: This is a straightforward and accurate description.

* Jack Russell Border Terrier: This is a more concise and easier to say version.

* Jack-a-Border: This is a playful and catchy name combining the names of the parent breeds.

Ultimately, the best name for your dog is the one you feel best describes their unique personality and appearance.