Rat Terriers come from a big mix of breeds: the extinct English White Terrier, Manchester Terriers, Smooth Fox Terriers, Whippets, Beagles, Italian Greyhounds, & Miniature Pinschers.
But they mainly...
All dog breeds can successfully mate and have puppies. The logistics can be a little hard though (ie how does a Maltese reach a Great Dane) but technically yes, it is possible. If the lab is female...
terriers have a lot of variances between breeds. some are short some are tall, some are energetic some are lazy, but by getting a dog with mixed breeding you get all of the good traits of the dog,...