Congenital polyalveolar lobe in three foals.

The research article is an exploration of three cases of a rare congenital condition called polyalveolar lobe (pulmonary hamartoma) found in female Thoroughbred foals. The research found that in all three cases, the right lung was affected, forming a tumor-like mass and led to health complications or death in the foals.

Overview of the Research

• The study discusses three unique cases of congenital polyalveolar lobe, a type of pulmonary hamartoma—in newborn female Thoroughbred foals. Pulmonary hamartoma is a rare, benign tumor formed in a lung, and this is the first time it has been reported in horses.
• The purpose of the study was to gain insights into the nature of this rare congenital condition and its effects on the health and survival of the foals affected by it.

Clinical Features of the Affected Foals

• Each foal presented different circumstances—Foal 1 was born at full term but unfortunately did not survive whilst Foal 2 was prematurely terminated at the seventh month. Foal 3 was induced at the tenth month due to a condition known as hydrops of the amnion and ascites – an abnormal accumulation of fluid in the abdomen.
• The research documents the anatomical changes in each case, noting the occurrence of the polyalveolar lobe on the right side impacting the entirety of the right lung leading to the formation of a tumor-like mass.
• This condition caused significant distortion of the normal anatomy, with the abnormal lung invading the left chest cavity, compressing the left lung and leading to a significant size and weight disparity between the two lungs.

Microscopic Observations

• Upon microscopic observation, the polyalveolar lobe featured ordinarily structured alveoli, bronchioli, and blood vessels. However, the ratio of alveoli to arteries was unusually high in the affected lung tissue.
• This abnormal ratio was confirmed by comparison to control lungs, where the ratio was significantly lower.
• Foals 2 and 3 exhibited chronic passive congestion with generalized oedema – a condition characterized by an excess collection of watery fluid in the cavities or tissues of the body.

Impact of the Research

• This research contributes to our understanding of rare congenital conditions in Thoroughbred foals and provides valuable insight into lived experiences and clinical presentations of foals with congenital polyalveolar lobe.
• The study emphasizes the need for further research to better understand the etiology and potential treatments of this rare condition.