Thrombocytopenia - Platelet issues in Cavaliers

“Platelets are also called thrombocytes. These are the blood cells that are responsible for normal blood clotting. Thrombocytopenia is an abnormally low blood platelet count.  Macrothrombocytes are abnormally large blood platelets.


Normal blood platelet counts should be between 150-200,000. Dogs will have bleeding abnormalities if their counts are below 40,000. However, the Cavalier King Charles Spaniel (CKCS) may have counts well below 40,000 with no problems. Approximately 30% of CKCS have macrothrombocytosis and/or thrombocytopenia. This appears to be a congenital abnormality. The CKCS does not experience any health problems despite these changes. It is thought that the large platelets of the Cavalier are able to provide the same function in lower numbers than that of other breeds. Because CKCS platelets are so large, automated cell counters may mistakenly count them as white blood cells, artificially lowering the platelet count. Additionally, these cells may not be recognized when examined under the microscope on a blood smear because they may not look like the platelets of other breeds.” Remember, the CKCS does not appear to experience any health problems due to this condition, which has only been reported in our breed and no others!


Copyright 2004 Dr. Kim Hamer DVM

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