Acute leukemia in six horses (1990–2012). (July 2017)

• Record Type: Journal Article
• Authors: Barrell, Emily A.; Asakawa, Midori Goto; Felippe, M. Julia B.; Divers, Thomas J.; Stokol, Tracy
• Is Part Of: Journal of veterinary diagnostic investigation. Volume 29:Number 4(2017:Jul.)
• Page Start: 529
• Page End: 535
• Publication Date: 2017-07
• Subjects: Acute lymphoblastic or myeloid leukemia -- equine; Veterinary medicine -- Diagnosis -- Periodicals; 636.0896075
• DOI: 10.1177/1040638717707724
• Languages: English
• ISSNs: 1040-6387

Abstract

Acute leukemia is rare in horses. Herein we describe historical, clinicopathologic, and postmortem findings in 6 horses with acute leukemia. Medical records of horses with >20% bone marrow blasts and cytochemical or immunophenotyping results were reviewed. Affected horses were 2–8 y of age and of different breeds and sex. Horses were presented acutely with nonspecific signs (e.g., fever, lethargy). Characteristic hemogram findings were bi- or pancytopenia with low blast numbers. Histologic examination revealed extramedullary infiltrates, especially in lymph nodes, spleen, kidney, liver, and lungs. Leukemias were classified as B-cell ( n = 3) and acute myeloid leukemia (AML) ( n = 3). Tumors in 4 cases expressed multiple lineage markers, which complicated classification. Acute leukemia should be suspected in horses with moderate-to-severe bi- or pancytopenia. Blood smears should be reviewed for neoplastic cells, and bone marrow examination is required for diagnosis. Leukemia classification is best achieved using combined morphologic, cytochemical, and immunophenotyping results.