Thanks, everyone - keep the comments coming. A little more background on this shot - the snowfall was fresh, and the clouds had just cleared out. The sun was out, but there happens to be a tall cottonwood just to the right of her, and an oak on the other side and it was just after 11am which gave me oddly enough less of a challenge with shadows. I was only about 15 feet away and there was so much clutter around (leaves, twigs, etc. from the storm), plus disturbed snow in front of her, that made cropping the shot a little difficult. But I'm going to go back to the original and see what I can do with that. Sensor dust? Yeah, maybe so. I had just bought the camera and supposedly it had been to Canon for a sensor cleaning but I don't think so - this shot brought it out. I should probably clone them out, huh?
Ron - thanks for the comment about my dog. She's one of several but has perfect Lab temperament - you can see it in her eyes. Your work on your website is marvelous - and you're a judge to boot. So am I - of Labrador Retrievers at AKC shows.
Thanks again, everyone - you've been very helpful! Oh - I would also like to hear more about the comment about white being blown. I sometimes struggle with that when working with snow.