OK, I know this may sound strange but I have 3 corgis that may be a little too skinny! I had Sage to the vet recently(low energy) and she checked out fine. Wynn and Bella also seem a bit thin also. You can feel their ribs but I know they should have a thin coat of muscle that you can feel over their ribs.They don't have worms either but do get plenty of exercise! I feed them Taste of the Wild, a grain free food a handful 3 times per day. I am thinking that feeding them a bit more would be good. Any thoughts?