MrPuck: My female GSD had the same symptoms you describe when she was coming down with cancer of the spleen (hemangiosarcoma). X-rays and regular blood work did not detect anything wrong. It was not until her cancerous tumors grew and could be detected by ultrasound that I finally knew what was going on. I agree that she should have a detailed blood panel, which checks the thyroid activity for one. Just be prepared that blood work, the more detailed it is, is very expensive.