title: Detection of activated platelets in dogs with primary immune-mediated hemolytic anemia.
abstract: Thromboembolism is a major cause of morbidity and mortality in dogs with immune-mediated hemolytic anemia (IMHA). To the authors' knowledge, the role of platelets in thromboembolic events associated with IMHA has not been extensively investigated. In the study reported here, we evaluated cell membrane expression of P-selectin with flow cytometry to determine whether platelets circulate in an activated state in association with primary IMHA. Median P-selectin expression for 20 dogs with primary IMHA was 8.1-fold greater, compared with values for 20 healthy dogs. Fifteen of 20 dogs (75%) with IMHA had P-selectin median fluorescence intensity (MFI) values that exceeded the reference interval for healthy dogs. Additionally, P-selectin MFI after activation of platelets with phorbol myristate acetate was 2.1-fold greater for dogs with IMHA than for healthy control dogs. Despite treatment of all dogs with immunosuppressive therapy and 18 dogs with subcutaneously administered low-dose unfractionated heparin, 7 dogs developed clinical signs consistent with thromboembolism. These data provide support for the hypothesis that platelets circulate in an activated state in many dogs with IMHA.
authors.affiliation: Department of Veterinary Biomedical Sciences, University of Minnesota, St Paul 55108, USA. weiss005@umn.edu
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Weiss
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Brazzell
mesh_terms: D000744:Anemia, Hemolytic, Autoimmune / Q000150:complications / Q000175:diagnosis / Q000662:veterinary*; D000818:Animals; D001780:Blood Coagulation Tests / Q000662:veterinary; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016022:Case-Control Studies; D004283:Dog Diseases / Q000097:blood / Q000175:diagnosis*; D004285:Dogs; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D008297:Male; D019007:P-Selectin / Q000378:metabolism; D010375:Pedigree; D015539:Platelet Activation / Q000187:drug effects; D011237:Predictive Value of Tests; D013755:Tetradecanoylphorbol Acetate; D013923:Thromboembolism / Q000097:blood / Q000150:complications / Q000662:veterinary
chemical_list: D019007:P-Selectin; D013755:Tetradecanoylphorbol Acetate