Gorgeous colors and lighting. Looks like you have a one pixel border thingie on top and bottom.. is a bit distracting (but not points-deduction-worthy). I really love this image and it is a ten from me.
To me, a portrait has controlled lighting and setting. Outdoor shots can work as a portrait but should not overwhelm the subject. I think it would help to tone down the blue and the green. The lighting seems too harsh, and the eyes are lost in shoadows.
If Prince Charles could be a dog, he'd be photographed in this type of setting! *evil grin* Really beautiful shot! I hope you've printed this out and framed it!
Nice. The lighting is a smidge harsh on the top of his nose. Wish the eye wasn't in shadow. Love the composition. I might crop and zoom in on him a bit more. He's lovely.