Suspected Tyzzer's disease in two foals.

Area of Science:

• Veterinary Pathology
• Equine Medicine
• Infectious Diseases

Background:

• Tyzzer's disease is a rare but severe condition affecting foals.
• Caused by Clostridium piliformis (formerly Bacillus piliformis).
• Often presents with acute hepatic necrosis.

Observation:

• Two foals, a Thoroughbred cross and an Arabian, presented with rapid onset illness.
• Clinical signs were brief, lasting only a few hours.
• Histological examination revealed liver lesions.

Findings:

• Diagnosis of Tyzzer's disease confirmed via histology.
• Microscopic findings included multiple foci of hepatic necrosis.
• Intracytoplasmic bacilli, consistent with Bacillus piliformis, were observed in hepatocytes.

Implications:

• Highlights the importance of histological diagnosis in suspected cases.
• Early identification of Bacillus piliformis is crucial for prognosis.
• Contributes to understanding the pathology of Tyzzer's disease in foals.