the mutt has drive energy seeping out in what has become a habit formed tension release, get him out using other avenues of drive, hunting , lamping ,mooching , ball play , tug play something that results in a positive interaction involving you and a huge use of energy
show and encourage him to express drive in other forms,
get him expressing it orally its most natural and feels better for the mutt,
Going out lamping tomorrow night on my new permission to see how he does