Congenital tumours and tumour-like lesions in domestic animals. 3. Horses. A review.

This research article provides a comprehensive review of the existing studies on congenital tumors and tumor-like lesions in horses, investigating the unique and more common types among horses, and exploring potential causes, including the potential role of oncogenic viruses.

Review of the Literature

The main focus of the research paper is an extensive review of the available literature on congenital tumours and tumour-like lesions in horses. These include:

• Embryonic tumours
• Teratomas
• Interstitial hamartomas
• Adenomatous hyperplasia of the placenta
• Benign teratoma of the undescended testis
• Congenital skin tumours that were of papillomatous, vascular, and melanocytic types

Unique Findings in Horses

The review highlighted some findings that seem unique to horses:

• Temporal teratomas, interstitial hamartomas, and placental adenomatous hyperplasia were found to be unique in horses, not commonly observed in other species.
• The benign teratoma of the undescended testis, which is a tumor that happens in the abdomen or in the inguinal region because the testicle didn’t descend, was observed to be far more frequent in horses than in other species.

Lack of Etiologic or Pathogenetic Clues

Despite the in-depth study, the nature of congenital tumors in horses still appears to be largely unknown:

• The rare nature of congenital tumours in horses impeded in identifying the etiologic (cause) or pathogenic (disease development) clues.
• The existence of oncogenic viruses, or viruses that can cause tumors, in cases of congenital skin papilloma or malignant lymphoma was explored, but evidence could neither be found to prove nor exclude this possibility.

Hereditary Tumours

The study revealed:

• No cases of hereditary tumours were discovered during the review, suggesting that these types of tumours are not common in horses, or that they might be underdiagnosed or unreported.