[Bilateral pleuritis following esophageal fistula in a horse as a complication of a Gasterophilus infection].

This research paper is about a case study of a pregnant Haflinger horse that died from bilateral pleurisy after being hospitalized for ten days, likely due to an infection with a Gasterophilus larva in the esophagus causing an ulcer and fistula.

Case Overview

• The study focuses on a six-year-old pregnant Haflinger mare, weighing in at 510 kilograms. Despite being treated with several antibiotics, the mare didn’t survive and perished after ten days in the hospital.
• The cause of death was discovered to be bilateral pleurisy, a condition where both of the mare’s pleural cavities (the thin spaces between the lungs and the chest) were inflamed.
• Post mortem analysis revealed the presence of a bilateral fibrinopurulent pleurisy. Fibrinopurulent pleurisy is an advanced stage of pleurisy where fibrin, a protein that aids blood clotting, and pus accumulate in the pleural cavity.

Discoveries

• Necropsy indicated an ulceration in the cardia of the stomach, a region close to the esophageal opening. The ulceration was approximately one square cm.
• A fistula, which is an abnormal connection between two body parts that are supposed to be separate, was discovered in the wall of the horse’s esophagus, near to the cardia.
• This fistula contained a third stage Gasterophilus larva. Gasterophilus is a genus of flies whose larvae are commonly known as horse bots. They typically infect the digestive systems of equines.
• Though there was a physical distinction between the fistula and the ulceration, the fistula was found to have a pathway to both pleural cavities, explaining the bilateral nature of the pleurisy.

Post-Mortem Microscopic Examination

• Under microscopic examination, an inflammatory infiltration was identified as the link between the fistula in the oesophageal muscular layers and the base of the cardiac ulcer.
• This discovery pointed to the implication of the Gasterophilus larva being the probable cause of the bilateral pleurisy. This is because the fistula could have provided an avenue for the larva and/or related bacteria to infect the pleural cavities, causing the observed inflammation and subsequent pleurisy.