Blood and bone marrow smears from 49 dogs and cats, believed to have myeloproliferative disorders (MPD), were examined by a panel of 10 clinical pathologists to develop proposals for classification of acute myeloid leukemia (AML) in these species. French-American-British (FAB) group and National Cancer Institute (NCI) workshop definitions and criteria developed for classification of AML in humans were adapted. Major modifications entailed revision of definitions of blast cells as applied to the dog and cat, broadening the scope of leukemia classification, and making provisions for differentiating erythremic myelosis and undifferentiated MPD. A consensus cytomorphologic diagnosis was reached in 39 (79.6%) cases comprising 26 of AML, 10 of myelodysplastic syndrome (MDS), and 3 of acute lymphoblastic leukemia (ALL). Diagnostic concordance for these diseases varied from 60 to 81% (mean 73.3 +/- 7.1%) and interobserver agreement ranged from 51.3 to 84.6% (mean 73.1 +/- 9.3%). Various subtypes of AML identified included Ml, M2, M4, M5a, M5b, and M6. Acute undifferentiated leukemia (AUL) was recognized as a specific entity. M3 was not encountered, but this subclass was retained as a diagnostic possibility. The designations M6Er and MDS-Er were introduced where the suffix "Er" indicated preponderance of erythroid component. Chief hematologic abnormalities included circulating blast cells in 98% of the cases, with 36.7% cases having>30% blast cells, and thrombocytopenia and anemia in approximately 86 to 88% of the cases. Bone marrow examination revealed panmyeloid dysplastic changes, particularly variable numbers of megaloblastoid rubriblasts and rubricytes in all AML subtypes and increased numbers of eosinophils in MDS. Cytochemical patterns of neutrophilic markers were evident in most cases of Ml and M2, while monocytic markers were primarily seen in M5a and M5b cases. It is proposed that well-prepared, Romanowsky-stained blood and bone marrow smears should be examined to determine blast cell types and percentages for cytomorphologic diagnosis of AML. Carefully selected areas of stained films presenting adequate cellular details should be used to count a minimum of 200 cells. In cases with borderline diagnosis, at least 500 cells should be counted. The identity of blast cells should be ascertained using appropriate cytochemical markers of neutrophilic, monocytic, and megakaryocytic differentiation. A blast cell count of > 30% in blood and/or bone marrow indicates AML or AUL, while a count of < 30% blasts in bone marrow suggests MDS, chronic myeloid leukemias, or even a leukemoid reaction. Myeloblasts, monoblasts, and megakaryoblasts comprise the blast cell count. The FAB approach with additional criteria should be used to distinguish AUL and various subtypes of AML (Ml to M7 and M6Er) and to differentiate MDS, MDS-ER, chronic myeloid leukemias, and leukemoid reaction. Bone marrow core biopsy and electron microscopy may be required to confirm the specific diagnosis. Immunophenotyping with lineage specific antibodies is i...

Thrombocytopenia was documented in 987 of 18,910 (5.2%) dogs admitted to North Carolina State University, College of Veterinary Medicine, Veterinary Teaching Hospital, between 1983 and 1989. Classifying thrombocytopenic dogs by etiologic groups revealed the following proportionate ratios: 5% (48/987) immune-mediated thrombocytopenia; 13% (130/987) neoplasia-associated thrombocytopenia; 23% (224/987) inflammatory/infectious thrombocytopenia; and 59% (585/987) miscellaneous thrombocytopenia. Dogs with immune-mediated thrombocytopenia had significantly (P < 0.05) lower platelet counts (mean 36,760 +/- 50,288 microliter) than dogs in the other three groups, and Doberman Pinschers were overrepresented in all groups except the immune-mediated thrombocytopenic group. We conclude that thrombocytopenia is a prevalent and potentially important diagnostic finding in a variety of disease states.

Background: Thrombocytosis has been associated with various conditions, including inflammation, neoplasia, iron deficiency, splenectomy, and drug administration. Objective: The aim of this study was to characterize diseases and conditions associated with thrombocytosis in dogs. Methods: In this retrospective study, dogs with thrombocytosis (platelet count > 600 9 10 3 /lL) and complete medical records during a 1-year period were included, and breed, sex, age, CBC results, alkaline phosphatase and gamma-glutamyltransferase activities in some dogs, administration of glucocorticoids or vincristine, and primary diagnosis were evaluated. Results: Thrombocytosis was found in 240 of 5342 dogs (4.6%), and 165 (3.1%) met inclusion criteria. Thrombocytosis was secondary in all dogs, and underlying diseases and conditions (n,%) were neoplasia (56, 33.9%), inflammation (55, 33.3%), miscellaneous disorders (26, 15.8%), neoplasia plus a second disease (13, 7.9%), endocrine diseases (8, 4.8%), and multiple diseases (7, 4.2%). In dogs with neoplasia, carcinomas (24) and round cell neoplasms (20), especially lymphoma and mast cell tumor, were the most frequent tumors. Inflammatory disorders consisted of immunemediated disorders (11), neurologic diseases (8), infectious diseases (6), allergic disease (5), orthopedic diseases (4), gastrointestinal diseases (4), and miscellaneous conditions (17). Of the 165 dogs, 73 (44.2%) had received glucocorticoids (55) or vincristine (18) Marked (850-969 9 10 3 platelets/lL) or extreme ( 970 9 10 3 platelets/lL) thrombocytosis occurred in 24 (14.5%) dogs; 12 (50.0%) had neoplasia. Thromboembolism occurred in 13 (7.9%) dogs. Conclusions: Thrombocytosis in dogs occurred most frequently secondary to neoplastic and inflammatory diseases and was commonly associated with glucocorticoid and vincristine administration. Thromboembolic complications occurred in a small number of patients. Marked or extreme thrombocytosis was more likely to occur with neoplasia than with other conditions.

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The presence of environmental contaminants in air, water and food may pose significant health risks to the exposed human population. However, problems associated with assessing chronic exposure to low doses of environmental chemicals, multiple exposure routes, diseases with long latency periods, and non-specific health outcomes make it difficult to conduct the appropriate human epidemiologic studies. It may be useful to complement human epidemiology with animal studies. Animals monitored or evaluated in situ for the appropriate suite of endpoints can provide information about both exposure levels and potential adverse health effects. Animals have served as sentinel indicators for health effects associated with a number of environmental exposures, including pesticides and asbestos. Pet dogs may be particularly valuable sentinels because they share the human environment. In addition, dogs respond to many toxic insults in ways analogous to humans, they have physiologically compressed life spans, and they are free from some important lifestyle risk factors for disease. An example of how pet dogs may be used as sentinels for potential human health hazards involves a study of the genotoxic effects resulting from exposure to a mixture of chemicals from nearby Superfund sites. We conducted a cross-sectional study of exposed dogs (living in the community with the Superfund sites) and controls (living in a nearby community). The pet owners completed a questionnaire, and we collected a blood sample from each dog. The blood samples were analyzed for standard clinical parameters and assays for possible genotoxic effects (peripheral blood lymphocyte micronucleus frequency and lymphocyte subtyping). Pet dogs living near the Superfund sites had a higher micronucleus frequency than control animals, suggesting that the dogs may have been exposed to environmental contaminants from these sites.

No abstract

The prevalence of feline thrombocytopenia (<200,000 platelets/m̈L) at North Carolina State University, College of Veterinary Medicine Teaching Hospital, from January 1985 to March 1990, was 1.2% (41/3300). Cats were divided into six categories based on clinical diagnoses: 29% (12/41) had infectious disease, 20% (8/41) had neoplasia, 7% (3/41) had cardiac disease, 2% (1/41) had primary immune‐mediated disease, 22% (9/41) had multiple diseases, and 20% (8/41) had disorders of unknown etiology. The mean platelet count for all thrombocytopenic cats was 52,000/μL ± 46,000/μL (1 SD) with a range of 1000–190,000/μL. No significant differences were found between groups with respect to platelet count, packed cell volume, or white blood cell count, though anemia and leukopenia were common among the cats as a whole. Bleeding disorders (hemorrhage or thrombosis) were observed in 29% (12/41) of thrombocytopenic cats and were more likely to be associated with neoplasia, cardiac disease, and platelet counts less than or equal to 30,000/μL. Disseminated intravascular coagulopathy was diagnosed in 12% (5/41) of the cats. Infections and/or neoplasia affecting the bone marrow were the most common diseases associated with thrombocytopenia. Feline leukemia virus and myeloproliferative neoplasia accounted for approximately 44% (18/41) of the specific diagnoses in thrombocytopenic cats. (Journal of Veterinary Internal Medicine 1993; 7:261–265. Copyright © 1993 by the American College of Veterinary Internal Medicine.)

Virtual microscopy (VM) uses a computer to view digitized slides and is comparable to using a microscope to view glass slides. This technology has been assessed in human medical education for teaching histology and histopathology, but, to the authors' knowledge, no one has evaluated its use in teaching cytopathology in veterinary medical education. We hypothesize that students will respond positively to the use of VM for viewing cytopathology preparations and that the technology can be successfully used for student assessment. To test this hypothesis, we surveyed students regarding their level of satisfaction with features of the VM system, their preference for use of VM in the curriculum, and the potential influence virtual slides may have on student study habits; student performance on a traditional cytopathology practical examination and a similar exam using VM was evaluated. Our results show that student perception of the VM system is generally very positive, with some concerns about resolution and the need for continued exposure to traditional microscopy. Within the curriculum, students indicated a preference for the option of using virtual slides for studying and take-home exercises. Overwhelmingly, students wanted either hybrid laboratory sessions or sessions using glass slides with virtual slides available for study and review. Students identified many VM test-taking features as advantageous compared with traditional glass-slide practical exams as traditionally administered. However, students indicated a strong preference for continued use of traditional microscopy for graded practical exams. Students may be more likely to study slides in preparation for practical examinations if virtual slides are available. Results also indicate that VM can be used successfully for assessment purposes, but students should receive training in using virtual slides if the technology will be used for assessment.