The Jack Russell Terrier takes its name from the Reverend John Russell, a nineteenth-century hunting parson in Devon, England, who bred mostly white fox-working terriers able to run with hounds and bolt foxes from their dens. Today's Jack Russells are compact, predominantly white dogs about 10 to 15 inches tall, with black or tan markings and smooth, broken or rough coats. The taller show type is registered in the United States as the Parson Russell Terrier.
Many Jack Russells are bold, clever, tireless and funny, with a huge prey drive and a talent for digging, climbing and escaping. They can be wonderful companions for active people who enjoy training and outdoor time, but they are rarely content as couch dogs. Daily vigorous exercise, mental challenges and firm, positive boundaries make the difference, and many shelter Jacks end up there because their energy was underestimated.