Pulmonary aspergillosis in a horse with myelomonocytic leukemia.

The study details a case of myelomonocytic leukemia in a young mare, complicated by pulmonary aspergillosis—an infection caused by the Aspergillus fungi.

Research Overview

The researchers came across a 2-year-old Standardbred mare diagnosed with acute myelomonocytic leukemia, along with non-responsive fever and hind limb edema. Several medical examinations followed the initial symptoms.

Disease Manifestation and Testing

• The researchers observed that the horse had anemia, thrombocytopenia (reduced platelet count), and leukocytosis (increase in the number of white blood cells) involving myeloblasts and monocytoid cells in circulation.
• A bone marrow sample extracted from the mare displayed excessive cellularity, again predominantly with myeloblasts and monocytoid cells, indicating the progress of the disease.
• Accompanying this diagnosis were significant detections of peroxidase, chloroacetate esterase, and alpha naphthyl acetate esterase activities in numerous bone marrow cells, providing more weightage to the leukemia diagnosis. Chloroacetate esterase and peroxidase in particular are valuable markers in diagnosing myelomonocytic leukemia.

Lung Issues and Radiography

• The team noted interstitial pulmonary densities during radiography, pointing to possible lung complications or infections. Interstitial lung diseases in horses are not common and require further analysis to confirm.

Euthanization and Autopsy Findings

• Given the gravity of the situation, the decision was taken to euthanize the mare. A subsequent necropsy or autopsy was performed for a more detailed understanding of the disease.
• They found infiltrates of leukemic cells in several specimens—including the spleen, lymph nodes, liver, kidneys, gastrointestinal tract, and lungs, affirming systemic involvement of leukemia.
• Notably in the lungs, the researchers observed granulomas containing fungal hyphae, and upon isolating these organisms, they identified the Aspergillus species. This detection led to the diagnosis of pulmonary aspergillosis, which is a severe infection of the lungs caused by the Aspergillus fungi.

This paper significantly contributes to the understanding of myelomonocytic leukemia in horses, detailing its symptoms, diagnostic techniques, and potential complications. Supported by necropsy observations, it unravels the complex interfacing of leukemia with a severe fungal lung infection—pulmonary aspergillosis.