Acute leukemia in six horses (1990-2012).

This research article is about several instances of acute leukemia in horses, detailing the diagnosis, clinical signs and results upon postmortem examination of six such cases.

Objective and Methodology

• The study was conducted to gain a deeper understanding of acute leukemia in horses, which happens to be a rare occurrence.
• Medical records of six horses that had a high percentage of bone marrow blasts and produced either cytochemical or immunophenotyping results were studied.
• The analysis involved historical data, clinical symptoms, postmortem outcomes, and importantly the process of evaluation and diagnosis of acute leukemia in horses.

Demographics and Presentation

• The horses studied ranged between 2 to 8 years of age, representing various breeds and both sexes.
• The common presenting symptoms were non-specific in nature such as fever and lethargy, mirroring an acute illness.
• A notable finding in the hemogram of these horses was the occurrence of bi- or pancytopenia (a reduction in the number of red and white blood cells and platelets) along with low blast cells numbers.

Diagnosis and Classification

• Upon histologic examination, extramedullary infiltrates (abnormal cells outside the bone marrow) were discovered in various parts of the body, notably in the lymph nodes, spleen, kidney, liver, and lungs.
• To classify the type of leukemia, the researchers divided the conditions as B-cell leukemia (3 cases) and acute myeloid leukemia (AML) (3 cases).
• However, the classification was challenging in certain conditions where tumors expressed multiple lineage markers.

Recommendation

• Based on the findings, the researchers recommend that acute leukemia should be suspected in horses presenting with moderate-to-severe bi- or pancytopenia.
• Blood smears should be critically evaluated for the presence of neoplastic cells and bone marrow examination is essential to make a timely and accurate diagnosis.
• For effective classification of leukemia, a combined approach using morphologic identification, cytochemical tracing, and immunophenotyping results is suggested.