This case is from a middle-aged dog that my associate saw. He had been vomiting frequently, so she took some radiographs of his stomach and chest. The ones from the chest were the most interesting. See if you can notice the problem here....
The vets reading this probably can see the issue. We have lots of training and experience in seeing subtle problems. For the laypeople, take a look at the parallel white lines through the chest. Here is the same image with some highlights to emphasize this.
See it now? This is a pretty big abnormality, and indicates an extremely abnormally large esophagus. Megaesophagus is most commonly diagnosed in younger dogs, and is usually the result of a persistent arch around the aorta that encircles the esophagus and crimps part of it. The esophagus is stretched so much over time that the muscle looses tone and it becomes very dialated. Other causes can lead to the same result, including metabolic disorders such as thyroid disease. Unfortunately, this is a permanent disorder where the muscle comprising the esophagus is too loose to be able to contract. This means that food can't go from the mouth to the stomach very easily, and requires life-long special feeding.
More orthopedic x-rays tomorrow.