Septic pleuritis and abdominal abscess formation caused by Rhodococcus equi in a foal.

The research article outlines a study about a 3-month-old Arabian horse that had fever, respiratory distress, lethargy, and decreased appetite. The diagnosis was pleural effusion and an abdominal abscess caused by the bacterium Rhodococcus equi, which was successfully treated with a combination of azithromycin and rifampin.

Research Context

• This study revolves around a young female Arabian horse that was suffering from a range of symptoms – fever, respiratory distress, lethargy, and decreased appetite – over a period of 5 days.
• The initial part of the research was the diagnosis of the animal’s condition, which revealed pleural effusion (a buildup of fluid between the layers of tissue that line the lungs and chest cavity) and an abdominal abscess.
• Rhodococcus equi, a type of bacterium, was identified as the causative agent for the diagnosed illnesses.
• This bacterium is known to typically result in pyogranulomatous pneumonia in foals, making pleural effusion an uncommon clinical sign of R. equi infection.

Methodology and Findings

• Diagnostic methods such as ultrasonographic and radiographic examinations were used to identify pleural effusion.
• The bacterium was identified through the cytologic examination of the pleural fluid and a bacteriologic culture, which yielded Rhodococcus equi.
• An intra-abdominal mass adjacent to the body wall of the horse was also identified with ultrasonography. Examination of this mass revealed purulent exudate (pus) that confirmed the formation of an abdominal abscess.
• Further bacteriologic culture of the exudate also revealed R. equi, confirming it as the culprit for both the pleural effusion and the abdominal abscess.

Treatment and Outcome

• The horse was treated with a combination of azithromycin and rifampin for a total of 8 weeks and also given metronidazole for 3 weeks.
• The young horse started showing signs of improvement within 2 weeks of commencement of the treatment.
• Further ultrasonographic examination at the end of 8 weeks showed resolution of both the pleural effusion and the abdominal abscess, proving that the treatment was successful.
• The combination of azithromycin and rifampin was deemed effective for treating R. equi infections in foals.