I was worried the first time I brought out my male tegu because I had heard the stories too but he was perfectly fine, didn't mind at all. The next day I brought my female out and immediately I knew something was wrong. She twisted out of my hands onto the lawn so I gave her a few minuets. When I tried to approach her she attacked with such speed I hardly got out of the way. It went on like for quite awhile until I finally dragged her back into the house by the leash. As soon as she was inside she was a total angel again. The next couple times I set her by the door and let her go out on her own. Now she's totally fine with being outside. I suggest you use a long leash the first couple times so you can keep your distance. Also I should mention that I tried about half a dozen various leashes from the pet store. The ones that did fit were a pain to get on them trying to put a strap behind the legs, in front of the legs, and across the two. My tegus didn’t like me fiddling with it so much and it still was hard to get it all tight. Now I’ve got a bunch of useless leather straps, strings, loops, and clamps lying around. The barrel clamps are so much easier to put on and tighten then the leashes I bought not to mention they’re less then a dollar. I got the idea from iguana forums there they call them "hip harnesses". Here's a pic of one of the leashes I bought that I used to use. I don't recommend that one.
