Canis ISSN: 2398-2942
Immune-mediated thrombocytopenia
Synonym(s): IMT, idiopathic thrombocytopenic purpura, ITP
Contributor(s): Prof Bernard Feldman
Introduction
- Most common cause of acquired defective hemostasis in dog.
- Cause: characterized by increased destruction of antibody coated platelets.
- Most often occurs as primary autoimmune disease but may occur secondary to infections, neoplasia or as an adverse reaction to medication.
- Treatment: glucocorticoids, platelet transfusion, is most difficult due to logistics and potential immune reaction, immunosuppressive therapy.
- Prognosis: good, rarely fatal.
Print off the owner factsheet on Immune-mediated thrombocytopenia Immune-mediated thrombocytopenia to give to your client.
Pathogenesis
Etiology
- Most often occurs as a primary auto-immune disease.
- Antibody-mediated platelet destruction may occur secondary to other disease processes or as a side-effect of medication.
Predisposing factors
General
- Following medication with:
- Sulfonamides.
- Cephalosporins.
- Penicillins.
- Phenylbutazone.
- Aspirin.
- Gold salts.
- Estrogens.
- Possible response following live-virus vaccination.
- Angiostrongylus vasorum infection Angiostrongylus vasorum.
Pathophysiology
- Accelerated destruction of antibody coated platelets → decreased circulating platelet lifespan.
- Thrombocytopenia develops when destruction is greater than production.
- Platelet production in bone marrow normally stimulated though in some cases anti-platelet antibodies cross react with megakaryocyes impairing production.
- Bleeding only occurs when platelet count is markedly reduced (<50 x 10*9/l).
- Thrombocytopenia -> defective primary hemostasis leading to petechial and ecchymotic hemorrhage.
- Secondary hemostasis remains intact.
Timecourse
- Development of thrombocytopenia is usually acute or sub-acute.
- Clinical signs invariably acute once thrombocytopenia developed.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Botsch V et al (2009) Retrospective study of 871 dogs with thrombocytopenia. Vet Rec 164 (21), 647-651 PubMed.
- Gould S M & McInnes E L (1999) Immune-mediated thrombocytopenia associated with Angiostrongylus vasorum infection in a dog. JSAP 40 (5), 227-232 PubMed.