What breed is Aspen again?

One of my dogs, Ozzy, is very skinny, but it's the Hound in him. He eats like a horse, but he also uses every calorie he takes in. Oz is in constant motion. He never stops long enough to gain any weight. He's perfectly healthy, just skinny.

Is Aspen active, playful? Does she drink enough water? Dehydration is much more dangerous than being strictly underweight.

What's her temperment like? I've found with nervous, anxious dogs it takes them much longer to gain weight. I truly believe that being nervous burns calories!

Paxil is really hard to keep weight on. I add plain old rice to her meals. She loves it and it's easy for her digest. As she has had pancreatitis, I can't add fat to her diet. The rice seems to be working for her.