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 esophageal mucosa caused by edema and congestion of the esophageal mucosa due to abnormal irritation of the tissue. 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 heal itself quickly. Prolonged use of a gastric tube, which irritates the esophagus, can also cause esophagitis. Excessive use of antibiotics for too long leads to infection caused by proliferation of fungi in the esophageal mucosa. Inflammation is caused by direct damage to the esophageal mucosa by swallowing hot food, sharp foreign objects or insufficiently chewed bones, and accidental ingestion of corrosive agents. When veterinary personnel give dogs and cats medication by gastric catheter, rough use of gastric catheter can often damage the esophageal mucosa.