Hepatic sarcocystosis in a horse.

The article is about a case of Hepatic sarcocystosis (protozoan infection) in a horse, which is coupled with multiple health issues including bacterial osteomyelitis, a plasma cell tumor, and hepatic salmonellosis.

Introduction to the Case

• The article details a case of Hepatic sarcocystosis in a horse, a disease caused by a parasitic infection in the liver.
• The horse in question also suffered from a multitude of health issues, including bacterial osteomyelitis (a form of bone infection), a plasma cell tumor in the maxilla (upper jaw or roof of the mouth), and hepatic salmonellosis (a bacterial infection affecting the liver).

Observed Lesions

• Multiple physical abnormalities were observed in the horse, such as effusions in the pleural, pericardial, and peritoneal cavities leading to fluid accumulation.
• The horse also displayed hepatomegaly (an enlarged liver), gastric ulceration, colonic edema (swelling in the colon), and tissue overgrowth in two maxillary dental alveoli (sockets in the upper jaw where teeth were previously located).

Microscopic Examination

• Under microscope examination, the liver displayed a severe suppurative necrotizing periportal hepatitis (pus-forming infection causing cell death around the area of the liver where vessels and nerves enter), and significant periacinar necrosis (cell death around air sacs).
• Protozoal schizonts (a form of the parasite) were frequently observed in different development stages in the hepatocytes (liver cells).
• These parasites displayed features typically associated with asexual division including an apical conoid and polar ring, anterior micronemes, central nuclei, and the absence of rhoptries (parasitic organelles).

Disease Characterization

• The observed disease characteristics did not correspond to the known pathogenic manifestations of Neospora caninum, Sarcocystis neurona, Toxoplasma gondii, or Hammondia hammondi, suggesting that it was caused by a different species of Sarcocystis.
• This is the first reported case of Sarcocystis-associated hepatitis in a horse. The life cycle of this particular Sarcocystis species and how the horse came to be infected are yet to be known.