How do you know you have a good catch dog?

Here the other day when we caught the little 150 lb boar I watched something a little different with Ol'Grip "my Dogo" that hog was in some blackberries and sprouts, and while I was stomping and wallowing around trying to get to where I could get hold of the hog I noticed Grip had a sprout about big as your thumb and a couple of blackberry vines almost that big in his mouth along with the hogs ear, it looked like he was bridled, the closer I got the more the hog tried to get away and he did, for just a split second, as the hog turned to run Grip grabbed the place nearest him which was right above the elbow on the front leg, he pulled back and swapped to the ear without any trash in his mouth this time and it was over. The only other time he's not been on the ear was when he was running a loose sow down by himself that came by us in some fairly open timber and everytime he'd start up beside her to where he could reach the ear she'd turn after about 3 tries he grabbed a hind leg and literally jerked her down and then swapped to the ear.