Fibrosis of the esophageal wall refers to the chronic and repeated damage of esophagitis that can cause destruction and fibrosis of the entire esophagus, resulting in esophageal strictures. Esophagitis refers to inflammation of the superficial or deep tissues of the esophageal mucosa caused by edema and congestion of the esophageal mucosa due to abnormal stimulation. Inflammation is caused by direct damage to the esophageal mucosa from swallowing hot food, sharp foreign objects or inadequately chewed bones, and accidental ingestion of corrosive agents. Veterinary personnel to dogs and cats with gastric catheters to instill drugs, rough use of gastric catheters, often can damage the esophageal mucosa. Physical or chemical esophagitis: The esophagitis reaction caused by radiation exposure is called radiation esophagitis. Drugs such as quinidine, tetracycline, potassium chloride, and iron can also cause esophagitis when they irritate the esophageal mucosa, especially when tablets stagnate in the esophagus. Esophagitis caused by overheated food can quickly resolve itself. Prolonged use of a gastric tube, which irritates the esophagus, can also cause esophagitis. Prolonged use of antibiotics leads to infection caused by proliferation of fungi in the esophageal mucosa.