Just popped into my head due to my crit. thread that this could be a good topic!
What do you consider too thin? I mean, if you're looking at a dog, what factors make a dog too thin to you?
Lacking muscle? Ribs, hips, spine showing?
If a dog's spine and every rib are showing, yet every muscle on the dog's body is easily showing and the dog is healthy and energetic, do you think it's underweight?
Here are some examples, different breed but I don't have permission from any GSD owners to use their pics..
You can see all of his ribs, and in some pics where he's running or something, his spine.. But look at the muscle tone. To me, this is a dog in great condition.
And then this shelter pup... His ribs and spine are showing the same as the above dog... However, do you see the muscle deterioration? The dog's body is taking nutrition from the muscles. that, to me, is an underweight dog.. Same skeletal structure showing, but there are other ways to tell if a dog is underweight. Look between the ribs, there is no muscle, not is there muscle on top of the ribs.. disgusting.
And check out this lab. Ribs highly visible. and spine in some pics, but check out the muscle on that boy.
Again - sorry I don't have GSD pics to use
With a lean dog, one with proper muscle, he's obviously getting proper nutrition to feed those muscles and keep him fit.. A skinny, or thin dog, would have obvious signs of being underfed - like weak or underdeveloped looking muscles. Regardless of bone showing... I know a little dog with a roached back that can have a pot belly and still show her spine.
My old shepherd, Mo, was certainly underweight. His ribs showed, his waist was sunken, his hips were very easily palpable (hidden by his fur), as was his spine. His muscles were deteriorated down to nothing. If he had good muscle mass and energy obviously I wouldn't have thought him underweight... He was 16 and dying for anyone wondering.
I keep no extra weight on my dogs. It serves no good purpose as my dogs are not outdoor dogs and don't need a layer of fat in the winter...
Now that I've given my thoughts on the matter, what are yours?