The research article discusses a seasonal syndrome of unknown origin present in horses that results in liver inflammation, identified through a study at a Midwestern veterinary teaching hospital.

Research Overview and Methods

• The research revolves around the examination of 13 horses over a 16-month period, exhibiting a new idiopathic (unknown cause) hepatitis syndrome. The horses showed symptoms like fever and raised blood liver enzyme activity.
• The study looked at medical records between December 1, 2020, and April 1, 2022, collected from client-owned horses. Researchers collected data about their medical history, clinical examination findings, clinical and lab test results, treatment methods used, clinical progress, and short-term results.

Findings and Observations

• The horses affected by this syndrome presented symptoms between December and April over the two seasons investigated, suggesting that this ailment possibly follows a seasonal trend.
• Most of the horses experienced recurring fevers over three weeks. During this phase, hepatological examination showed signs of liver inflammation. The tissue inflammation was characterised by hepatic necrosis, neutrophilic to lymphohistiocytic inflammation, biliary epithelial damage, and portal fibrosis.
• Further indications of systemic inflammation in the diseased horses were observed by increased concentration of serum amyloid A and variations in the leukons.
• None of the horses displayed signs of hepatic insufficiency, and all clinically recovered. By approximately 16 weeks, the activity levels of GGT (an enzyme indicating liver disease) in most horses returned to normal.
• Even though the horses clinically recovered, some histologic signs of the disease, such as tissue changes or damage remained detectable up to 27 weeks after initial presentation in one particular horse.

Conclusion and Further Inference

• The study characterized a seasonal equine hepatitis syndrome marked by fever, systemic inflammation, increased liver enzyme activity, and histologic evidence of hepatitis.
• While the exact causative agent was not identified in this study, the findings based on the histology and outcome suggest that an infectious agent might be responsible for this disease.