My terrier went to ground in a rabbit warrren where cubs had to been reared . He dug on in the sandy ground for four days . Had no collar on him as i was just out checking holes for the farmer to keep him happy . I dug him about 2.00 Pm on the forth day . Took him out but he wanted to go back in . I think he dug him self in and the holes where to tight to turn and dig out so he had to keep digging forward