Peer-reviewed veterinary case report
Horse with immune low platelets treated successfully with vincristine
By Salewski, K E et al.·Published in Journal of equine veterinary science·2026·Department of Pathobiology and Population Medicine, United States·View original on PubMed →
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Original publication title: Successful use of vincristine in a quarter horse gelding with immune-mediated thrombocytopenia.
- Species:
- horse
Plain-English summary
A 15-year-old Quarter Horse gelding developed a high fever and severe bruising after a skin graft procedure. Blood tests showed he had a dangerously low platelet count, which can lead to serious bleeding issues. After ruling out infections and other causes, the vet treated him with several medications, including vincristine, which helped stimulate the production of platelets. Remarkably, his platelet count improved and eventually returned to normal, making this case one of the few successful treatments for immune-mediated thrombocytopenia in horses using vincristine.
People also search for: horse low platelet count treatment · Quarter Horse fever and bruising · vincristine for horses
Abstract
This case reports the successful use of vincristine in a Quarter Horse with presumed immune-mediated thrombocytopenia. A 15-year-old Quarter Horse gelding presented for a pinch skin graft procedure on the left forelimb over the cannon bone. On day 10 of hospitalization, the horse developed a fever (102.6°F, RI: 99-101°F), and severe petechiae of the mucous membranes. A complete blood count (CBC) (Advia 2120i) revealed a severe thrombocytopenia (16,000 platelets/μL, RI:100,000-400,000/μL). Diagnostic testing was negative for Anaplasma phagocytophilum by PCR, Theileria equi and Babesia caballi by cELISA, and equine infectious anemia (EIA) virus by agar gel immunodiffusion. A sternal bone marrow aspirate was suggestive of megakaryocyte hypoplasia. However, the sample was not of good quality and was suspected not to be a good representation of the marrow. Over a 20-day treatment period, the horse received multiple immunosuppressive medications (dexamethasone, prednisolone, azathioprine) and vincristine in attempt to improve the thrombocytopenia. Following vincristine administration, the platelet count increased substantially and eventually normalized. Vincristine is thought to stimulate thrombopoiesis and increase megakaryocyte fragmentation within the bone marrow. Based on response to vincristine, exclusion of infectious agents, and lack of a consumptive process (e.g., disseminated intravascular coagulation [DIC], chronic hemorrhagic lesion), a presumptive diagnosis of immune-mediated thrombocytopenia (IMTP) was made. To the authors' knowledge, this is one of only two reported cases in equine medicine describing successful treatment of IMTP with vincristine. This case report offers novel treatment information, previously well documented in domestic small animals.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/41962605/