Small intestinal adenomatous polyposis resulting in protein-losing enteropathy in a horse.

The research article presents a case of a 4-year-old Quarter Horse with small intestinal adenomatous polyposis that resulted in protein-losing enteropathy, characterized by significant weight loss and other physical conditions.

Case Presentation

• The subject horse had been suffering from weight loss for a duration of 6 months and was also experiencing extensive ventral subcutaneous edema.
• Testing revealed that the horse had a notably low serum total protein (2.9 g/dl) and a low packed cell volume (24%).

Observations and Findings

• The distal jejunum and the entire ileum sections of the horse’s intestines were covered with numerous abnormal growths of varying shapes, composed mainly of tall columnar cells and a large number of goblet cells.
• These growths exhibited neoplastic changes throughout their mucosa, although a clear boundary was observed between neoplastic masses and adjacent mucosa.

Immunohistochemical and Microscopic Examination

• Immunohistochemical staining for p53 tumor suppressor protein revealed sporadic cytoplasmic reactivity within the abnormal growths and normal tissues.
• There were no nuclear stains for papillomavirus antigens, which indicates that the horse was not suffering from a viral infection.
• Electron microscopic examination revealed the presence of well-differentiated intestinal epithelial cells, with features including apical tight junctions and microvilli, desmosomes, and the presence of numerous goblet cells. There were no signs of microorganisms, which rules out any bacterial or similar infection.

Conclusion

• This case report concludes that small intestinal polyposis should be considered a rare potential cause of protein-losing enteropathy in horses.