Terminology:
1. Platelets are also called thrombocytes. These are the blood cells that
are responsible for normal blood clotting.
2. Thrombocytopenia is an abnormally low blood platelet count.
3. 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,
Cavaliers may have counts well below 40,000 with no problems.
Approximately 30% of Cavaliers have macrothrombocytosis and/or
thrombocytopenia. This appears to be a congenital abnormality. The Cavalier
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 Cavalier 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.
This condition should not be confused with immune-mediated
thrombocytopenia, where the body attacks its platelets. Dogs with this
disorder will be having SYMPTOMS: i.e. petechiae, bruising and bleeding.
Remember, the Cavalier does not experience any health problems due to
this condition which has only been reported in our breed and no others!
Kim Hamer D.V.M.
