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Thank you to Patti Emmett, MS, RN, CIC for putting together and updating this article for SCARF.
Immune-Mediated Thrombocytopenia is a decreased numbers of blood platelets due to platelet destruction by the immune system.
Signs and Symptoms
Spontaneous visible bruising is the major clinical sign. Small spidery spots of bruising clustered together are called “petechiae”. Petechiae are the most common sign. Larger purple areas of bruising are called “ecchymosis”.
In many cases, a cause isn’t found. In some cases, a primary reaction by the immune system precedes the act of platelet destruction.
Examples of reactions in the immune system that could be followed by platelet destruction include:
- a parasitic infection of blood (Ehrlichiosis, Rocky Mountain Spotted Fever)
- a tumor
- drugs (chemotherapy agents, sulfonamide and chloramphenicol antibiotics)
- exposure to ticks and tick-borne blood parasites
- pre-existing Lupus
- a diagnosis of bone marrow cancer
- certain treatments for cancer and infections
Inspection of gums and mouth, whites of the eyes, and abdomen may reveal petechiae or ecchymosis. Blood platelet counts can determine if numbers of platelets are normal or too low, or appear abnormal. Veterinarian diagnosis on a case-by-case basis, using tests for other diseases combined with symptom assessment. A test is not yet commercially available in the United States to detect anti-platelet antibodies in dogs. A test is available for humans, and for dogs in the UK.
Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.
Treatment of the cause, if known
Prednisone or dexamethasone immunosuppression
Azathioprine if no response to above
Transfusion when a crisis occurs
Plasma exchange has been cited as an emerging treatment. Improvement of hemorrhages occurred in a small number of dogs in a research report.
- Barlough,J.E., Pedersen, N.C, 1995. “The immune system and disorders” in UC Davis School of Vet Med book of dogs. Siegal, M. Ed., p.331-333. Harper Collins, New York.
- Williams,D.A., Maggio-Price, L., 1984. Canine idiopathic thrombocytopenia: clinical observations and long-term follow-up in 54 cases. J Am Vet Med Assoc 15; 185(6):p.660-663. Link to abstract
- Kohn, B., 2003. Immune-mediated thrombocytopenia – current approach. 28th World Congress of World Small Animal Veterinary Assoc, Thailand p.1-3.
- Trepanier, L.A., Danhof, R., Toll, J., and Watrous, D. Clinical findings in 40 dogs with hypersensitivity associated with administration of potentiated sulfonamides. J Vet Int Med 9; 2003 Sep-Oct; 17(5):p. 647-652. Link to abstract
- Shropshire S, Dow S, Lappin M, 2020. Detection and dynamics of anti-platelet antibodies in thrombocytopenic dogs with and without idiopathic immune thrombocytopenia. J Vet Intern Med; 34(2): 700-709.
- Kopecny L et al, 2020. Application of Therapeutic Plasma Exchange in Dogs with Immune Mediated Thrombocytopenia. J Vet Int Med; er(4): 1576-1581