Purpura is a large area of purplish or brownish red discoloration, easily visible through the skin, caused by bleeding into the tissues. In humans, immune-mediated thrombocytopenic purpura (ITP) is one of the most common forms of autoimmune disease affecting both adults and children. The resulting Immune-mediated thrombocytopenia (IMT) is associated with autoantibodies that are directed against various platelet membrane receptors, including platelet glycoproteins, such as glycoprotein IIb/IIIa (GPIIb/IIIa) or GPIb/IX complexes. Binding of autoantibodies to these target antigens eventually results in platelet destruction by the reticuloendothelial system.
Autoimmune thrombocytopenic purpura (ATP) occurs in acute and chronic forms. Affected adults generally have the chronic variety that is marked by bleeding from mucous membranes (mouth and nose), gastrointestinal tract, and urinary bladder. Affected animals usually bruise easily and have prolonged bleeding after trauma. Canine ATP has been described in the Poodle, German Shepherd Dog, English sheepdogs and Cocker Spaniel. Treatment is directed toward maintaining the patient free of purpura, not restoring the platelet count to normal. The standard choice of treatment is corticosteroids. Other therapies, such as the immunosuppressive drugs azathioprine, cyclosporine, and leflunomide, may also be considered. In cases of recurring IMT, splenectomy, vincristine, and human intravenous immunoglobulin can be considered. Vincristine is thought to increase platelet counts in patients with IMT. Compared to prednisone, administration of vincristine rapidly increases platelet numbers and shortens the duration of hospitalization for IMT dogs.4 However, in the chronic form of the disease, cessation of therapy results in eventual relapse.
- S Karpatkin. Autoimmune thrombocytopenic purpura. Volume 56, Issue 3, pp. 329-343, 09/01/1980
- Mei Chang, Peggy A. Nakagawa, Shirley A. Williams, Michael R. Schwartz, Karen L. Imfeld, Jeffrey S. Buzby, and Diane J. Nugent. Immune thrombocytopenic purpura (ITP) plasma and purified ITP monoclonal autoantibodies inhibit megakaryocytopoiesis in vitro. The American Society of Hematology. Blood, 1 August 2003, Vol. 102, No. 3, pp. 887-895
- Bernard F. Feldman, Joseph G. Zinkl, Nemi Chand Jain. Schalm's Veterinary Hematology
- Application of vincristine-loaded platelet therapy in three dogs with refractory immune-mediated thrombocytopenia