Is that a rat terrier. We had one (who had to be rehomed when she moved.) She now keeps the floor clean for a family of 14 plus grandma. Great dog for kids and old folks. Not to bright, but means well. Fits in lap.
Jack Russell. Big dog in a small package.
Rat Terrier. I’ve had them all my life and the ones I’ve had have been VERY smart. They also have no congenital (breed) health problems. And unlike Jack Russels, they have an “off switch.”