Judy,
I had to go find this in my "Bookmarks" but finally did. So here are the instructions for the shirt.
MAKE: Blog: HOW TO - Make a dog sweater from a sock
On the directions, it doesn't instruct you to stitch around the leg openings and at the end of the sock where you cut. I stitch it because after they are cut, the sock tends to fray after wearing and washing and the leg openings get really big and your baby's legs fall out.
I hope this helps some.