Acute Leukemia in Horses.
Abstract: Leukemia is broadly divided into acute and chronic lymphocytic and myeloid types based on the proportion of blasts, morphology of cells, and expression of specific antigens on neoplastic cells. Classifying leukemia in horses can be challenging if blasts predominate and since few antibodies to identify cell types are available. The objective of this study was to describe in detail the clinical and pathologic features of acute leukemia in horses. Twelve horses ranging from 0.2 to 25.9 years of age were diagnosed with acute leukemia. Six cases were classified as acute lymphocytic leukemia (ALL) based on predominance of blasts, lack of granulocytic or monocytic differentiation, and detection of CD3, CD20, and/or CD79a antigens by immunohistochemistry. Six other cases were classified as acute myeloid leukemia (AML) with myelomonocytic ( n = 4), basophilic ( n = 1), and eosinophilic ( n = 1) differentiation based on > 20% bone marrow blasts and partial leukocytic differentiation. Reactivity with antibodies to Iba-1/AIF-1, CD172a, and CD163 was determined for all cases of AML. Eleven horses had thrombocytopenia, 10 had neutropenia, 8 had anemia, all had blasts on blood films, and none had leukocytosis. Ten horses had increased serum acute phase proteins. Bone marrow cellularity ranged from 30% to 100%, and the proportion of blasts ranged from 80% to 100% and 30% to 60% in ALL and AML, respectively. Horses were severely ill at diagnosis and euthanized within days or weeks. Unique features of acute leukemia in horses compared to other species were variable lymphocyte antigen expression (ALL) and frequent inflammation (ALL and AML).
Publication Date: 2017-08-16 PubMed ID: 28812528DOI: 10.1177/0300985817720983Google Scholar: Lookup
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- Journal Article
Summary
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This study pertains to the classification, clinical and pathological features of acute leukemia in horses. Using a sample of twelve horses, the research identified six cases each of acute lymphocytic leukemia (ALL) and acute myeloid leukemia (AML) based on a number of markers and symptoms.
Classification of Leukemia in Horses
- Leukemia involves a division into either acute or chronic lymphocytic and myeloid types. The categorization is contingent upon the proportion of blast cells, the cell morphology, and the expression of specific antigens on the neoplastic cells.
- However, the classification for horses can be a challenging process especially when blasts predominate and due to the limited availability of antibodies to detect different cell types.
Results & Observations
- Out of twelve horses diagnosed with acute leukemia, six had acute lymphocytic leukemia (ALL). This was based on the predominance of blast cells, absence of granulocytic or monocytic differentiation, and the detection of CD3, CD20, and/or CD79a antigens with the use of immunohistochemistry.
- The other six horses were diagnosed with acute myeloid leukemia (AML), with myelomonocytic (four cases), basophilic (one case) and eosinophilic (one case) differentiation. This was based on an excess of 20% bone marrow blasts and partial leukocytic differentiation.
- The antibodies Iba-1/AIF-1, CD172a, and CD163 showed reactivity in all the AML cases.
Systemic Effects and Euthanization
- Common systemic effects seen in these horses included thrombocytopenia (11 horses), neutropenia (10 horses), and anemia (8 horses), with no cases of leukocytosis.
- All of the horses displayed high levels of blood blasts and had significantly increased levels of acute phase proteins in the serum, which are markers of inflammation and often indicate underlying disease.
- The bone marrow cellularity varied from 30% to 100% and the proportion of blast cells ranged hugely, from 80% to 100% in ALL and from 30% to 60% in AML.
- Given the severity of their illnesses, the horses were euthanized after diagnosis within a matter of days or weeks.
Unique Features of Acute Leukemia in Horses
- Distinct features of acute leukemia in horses as compared to other species were the variable lymphocyte antigen expression in ALL and frequent inflammation in both ALL and AML.
Cite This Article
APA
Cooper CJ, Keller SM, Arroyo LG, Hewson J, Kenney D, Bienzle D.
(2017).
Acute Leukemia in Horses.
Vet Pathol, 55(1), 159-172.
https://doi.org/10.1177/0300985817720983 Publication
Researcher Affiliations
- 1 Department of Clinical Studies, University of Guelph, Guelph, Ontario, Canada.
- 2 Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada.
- 1 Department of Clinical Studies, University of Guelph, Guelph, Ontario, Canada.
- 1 Department of Clinical Studies, University of Guelph, Guelph, Ontario, Canada.
- 1 Department of Clinical Studies, University of Guelph, Guelph, Ontario, Canada.
- 2 Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada.
MeSH Terms
- Animals
- Disease Progression
- Horse Diseases / classification
- Horse Diseases / pathology
- Horses
- Leukemia / classification
- Leukemia / pathology
- Precursor Cell Lymphoblastic Leukemia-Lymphoma
- Thrombocytopenia / pathology
Citations
This article has been cited 7 times.- Satué K, Gardon JC, Muñoz A. A review of current knowledge of myeloproliferative disorders in the horse. Acta Vet Scand 2021 Feb 23;63(1):8.
- Lee GKC, Bienzle D, Keller SM, Hwang MH, Darzentas N, Chang H, Rätsep E, Egan R, Beeler-Marfisi J. Use of immune repertoire sequencing to resolve discordant microscopic and immunochemical findings in a case of T cell-rich large B cell lymphoma in a young dog. BMC Vet Res 2021 Feb 18;17(1):85.
- Suzuki S, Ogino N, Mitsui I, Ito H, Kariya T. Anti-CD71 antibody immunohistochemistry in the diagnosis of acute myeloid leukemia, subtype acute erythroid leukemia with erythroid dominance (AML M6-Er), in a retrovirus-negative cat. J Vet Diagn Invest 2021 Jan;33(1):87-94.
- Satué K, Gardon JC, Muñoz A. Clinical and laboratorial description of the differential diagnoses of hemostatic disorders in the horse. Iran J Vet Res 2020 Winter;21(1):1-8.
- Carpenter AL, Townsend KS, Johnson PJ, Kim DY. Disseminated pleomorphic rhabdomyosarcoma in a horse. J Vet Diagn Invest 2025 Jan;37(1):203-207.
- Lee J, Mordoh S, Mirza M, Carossino M, Del Piero F. Acute myeloid leukemia-M1 in a horse with neurologic signs and necrotizing enterocolitis. J Vet Diagn Invest 2024 Nov;36(6):836-841.
- Costa VR, Soileau AM, Liu CC, Moeller CE, Carossino M, Langohr IM, Withers SS. Exploring the association of intratumoral immune cell infiltrates with histopathologic grade in canine mast cell tumors. Res Vet Sci 2022 Oct;147:83-91.
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