Multicavitary septic effusions associated with actinobacillosis in an adult Tennessee Walking Horse with weight loss
Authors: Means K., Townsend K., Johnson P.
Journal: Equine Veterinary Education
Summary
# Editorial Summary An 18-year-old Tennessee Walking Horse gelding presented with an atypical manifestation of actinobacillosis, exhibiting progressive weight loss over six months whilst lacking the classical acute clinical signs usually associated with this infection. Transabdominal and thoracic ultrasonography identified multicavitary effusions in both the peritoneal and pleural spaces, enabling diagnostic fluid collection that confirmed actinobacillosis through microbiological culture. Notably, haematological parameters remained unremarkable despite concurrent peritonitis and pleuritis—a departure from typical presentations where leucocytosis, neutrophilia or leucopenia are commonly documented. Following percutaneous drainage of both cavities and broad-spectrum antimicrobial therapy, the gelding recovered completely. This case highlights the importance of including actinobacillosis in the differential diagnosis for weight loss in adult horses, particularly when ultrasonography reveals effusions but systemic inflammatory markers are unexpectedly mild, as insidious presentations without fever, acute colic or respiratory signs may mask this potentially serious infection.
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Practical Takeaways
- •Include actinobacillosis in differential diagnoses for chronic weight loss in adult horses, even without fever or acute clinical signs
- •Use ultrasonography to identify and sample peritoneal and pleural effusions when investigating unexplained weight loss; fluid analysis is essential for diagnosis
- •Prompt drainage of infected fluid combined with appropriate antimicrobial therapy can result in complete recovery even in advanced cases
Key Findings
- •An 18-year-old Tennessee Walking Horse presented with progressive weight loss over 6 months as the sole clinical abnormality, later diagnosed as actinobacillosis with peritonitis and pleuritis
- •Peritoneal and pleural effusions were successfully identified and sampled via ultrasonography, enabling microbiological diagnosis
- •The horse made complete recovery following drainage of fluid from peritoneal and pleural spaces combined with broad-spectrum antimicrobial therapy
- •Actinobacillosis can present atypically in adult horses without fever, acute colic, respiratory signs, or haematological abnormalities