Hepatic encephalopathy in a pregnant mare: identification of histopathological changes in the brain of a mare and fetus.

The research paper is examining a case of hepatic encephalopathy in a pregnant horse, detailing the symptoms and diagnostic findings, treatments administered, and the eventual deterioration that led to euthanasia, alongside postmortem examinations.

Disease Identification and Assessment

• This research followed the case of an 11-year-old Thoroughbred broodmare who showed clinical signs of hepatic encephalopathy. Initial assessment included an ultrasonographic evaluation, which revealed changes in the liver such as increased size and rounded borders.
• No evidence of gallstones (cholelithiasis) or dilatation of the bile duct was presented at this point. In addition to the physical assessment, an increase was noticed in various measures, including the activity of hepatic enzymes, the concentration of bile acid and bilirubin, and the concentration of ammonia. These increases corroborated the suspicion of hepatic disease and hepatic encephalopathy.
• A liver biopsy led to a histopathological investigation. The results were consistent with chronic active hepatitis, which is a long-term liver inflammation condition.

Treatment and Disease Progression

• The mare’s treatment included intravenous fluids, antimicrobials, pentoxyfilline (a drug known to increase the flexibility of red blood cells and decrease inflammation), branched-chain amino acids and dietary manipulation.
• Noticeable improvements were observed initially, however, three weeks later, the mare’s condition deteriorated significantly, ultimately leading to euthanasia.

Postmortem Examination and Findings

• Necropsy, the postmortem examination of the mare, revealed that disease-related changes were limited to the liver and brain.
• The liver showed distinctive hardness across its structure, exhibiting a notable reticular pattern on the surface. Additionally, a large gallstone (choledocholith) was identified in the main bile duct of the left liver lobe.
• Microscopic examination of liver tissue disclosed extensive fibrosis (excessive amounts of connective tissue), increased bile duct growth, and inflammation characterized by mononuclear cells and neutrophils.
• In both the cerebrum of the mare and her fetus, pathological changes that are consistent with hepatic encephalopathy were observed. This key finding presented as Alzheimer type II cells, demonstrating the impact of the mare’s liver pathology on her brain and her unborn foal’s brain.