Mars’ pet food linked to megaesophagus outbreak. A Melbourne University study has found a statistical link between the Advance Dermocare pet food and an outbreak of a debilitating and incurable illness in dogs throughout Australia. Megaesophagus causes the esophagus to become enlarged and limits the movement of food and liquid to the stomach. If dogs survive, they must be fed upright so the food does not get stuck in their esophagus.