Aim: The aims of this study were first to estimate calcification in the esophagus and abomasum of cows and second to quantify its appearance with increasing age using histopathological and immunohistochemical techniques.

Materials and Methods: Esophageal and abomasal samples from 24 healthy cows (Bos taurus) were collected. Hematoxylin and eosin, alizarin red, and von Kossa stains were used for histopathological analysis. Histopathological changes were confirmed with immunohistochemical staining, followed by digital image analysis.

Results: Histological findings revealed the esophagus and abomasum wall comprised four fundamental layers, the mucosa, submucosa, muscularis, and serosa or adventitia. At 1 year old, calcification was beginning to appear as fine diffused points in mucosa, submucosa, and muscularis of both esophagus and abomasum, appearing as small spots at 2 years old. With advancing age in all animals, this calcification began to appear as medium spots spread throughout all wall layers of these organs at 3 years old. By 4 years old, calcification had evolved into large dark foci spread substantially throughout the tunica submucosa and tunica muscularis. Immunohistochemical results exhibited positive immunoreaction to calcium salts in the esophagus and abomasum layers in all animals, which increased with age.

Conclusion: The current study concluded that calcification is a pathological event appearing spontaneously in various types of soft tissue, significantly increasing with age, either because of hypercalcemia and hyperphosphatemia or secondary to other diseases.

Keywords: abomasum, alizarin red, calcification, esophagus, immunohistochemistry, von Kossa.