Acute hemorrhagic pulmonary infarction and necrotizing pneumonia in horses: 21 cases (1967-1993).

This research explores cases of acute hemorrhagic pulmonary infarction and necrotizing pneumonia in horses, particularly Thoroughbred racehorses, investigating the history, symptoms, and pathological data.

Methods and Sample Population

• The study adopted a retrospective method, examining 21 cases with a history of acute hemorrhagic pulmonary infarction and necrotizing pneumonia confirmed by histology.
• Of these 21 horses, 19 were Thoroughbred racehorses currently undergoing training.

Primary Observations

• Under high-stress situations such as strenuous exercise, 18 out of 21 horses began displaying signs of illness.
• During their hospital stay, 15 horses had a serosanguineous (bloody) nasal discharge.

Radiographic and Ultrasonographic Evidence

• Seventeen horses presented radiographic evidence of pulmonary consolidation and pleural effusion.
• Out of 14 horses, 9 showed large pulmonary parenchymal defects through ultrasound, consistent with consolidation.
• Pleurocentesis, a procedure to remove fluid from the space between the lungs and the chest wall, revealed a suppurative, serosanguineous effusion in 14 cases.

Bacterial Isolation

• From all transtracheal aspirates (14 in total), bacteria were isolated, and also from 6 out of 12 pleural fluid samples.
• The bacteria most typically isolated were Actinobacillus suis-like organisms and Streptococcus equi subsp. zooepidemicus.

Treatment, Duration, and Outcome

• 19 of the horses were hospitalized and underwent treatment, with an average duration of 5 days.
• Unfortunately, most horses had to be euthanized due to ongoing medical costs, secondary complications, or a bleak prognosis for future performance.

Pathological Lesions Observed

• Post-mortem examinations uncovered well-defined regions of hemorrhagic pulmonary infarction with necrosis and serosanguineous pleural effusion.
• Pulmonary blood vessel thrombosis was found in 11 horses.

Conclusions Drawn

• The research concludes that an sudden onset of severe breathing distress, coupled with a serosanguineous nasal discharge, as well as ultrasonographic and radiographic evidence of heavy pulmonary consolidation and serosanguineous suppurative pleural effusion, strongly indicates pulmonary infarction in horses.
• Worryingly, horses suffering from pulmonary infarction responded poorly to conventional pleuropneumonia treatment and generally had a poor recovery prognosis.