I also had difficulties getting Scottie to come when called outdoors. He was relatively okay coming indoors, but there are just too many more interesting things outsides. I had tried many treats to no avail (even cooked chicken) - I think the smells of most treats weren't as exciting as nature's smells.
Finally, I found that
green tripe worked for him. It's extremely stinky in the dehydrated form. It's actually really disgusting but has a lot of health benefits (for dogs). Looks like this:
http://www.truecarnivores.com/wp-con...4/04/tripe.jpg
Because the smell is so strong and it actually got his attention. I used a very long rope to tie onto his harness. While stepping on one end, I called him to come whenever he went far and treated him with the green tripe when he came to me and let me hold onto his harness.
Gradually, I let him run around with the long rope and doing the same: calling him to come, grabbing his harness and treating him the green tripe. It was important for me to grab his harness, because otherwise he'd try to outsmart me and would take the treat and run away.
When I felt he was coming most of the time, I removed the rope and continue to bring the green tripe with me at any time I let him run around outside. If I didn't bring the treat with me, he didn't get to roam off-leash outside. This was done over a period of a couple months last summer. Once it's a very reliable recall, you can start to wean him off the treats.
Make sure you never ever ever get mad at him for coming to you, whether indoors or outdoors, even if he had done something bad, or if he finally came to you after you called him 20 times. Always always make a party out of it for him coming to you (even if you were mad at him). They need to feel the positive connection for coming to you each and every time
