Introduction
Polycythemia in cats is a condition in which the number or concentration of circulating red blood cells in the body is increased. Polycythemia is also known as erythrocytosis. The symptoms and treatment of polycythemia can vary greatly and depend on why the condition developed. There are two types of polycythemia, relative and absolute, that can occur in cats.
Types of Polycythemia
Relative Polycythemia
Relative polycythemia is a condition in which the red blood cell numbers are increased due to a large loss of plasma, or water, from the bloodstream, or due to a release of large amounts of red blood cells into the bloodstream. In this condition no extra red blood cells are produced by the cat’s body. For example, severe vomiting or diarrhea can result in dehydration which then causes relative polycythemia. Transient polycythemia is a type of relative polycythemia that occurs when a cat experiences extreme excitement or fear; these emotional states, if severe, can lead to a contraction of the spleen which releases a high amount of red blood cells into the bloodstream.
Absolute Polycythemia
Absolute polycythemia is either primary or secondary. Primary absolute polycythemia occurs from a bone marrow disease which causes increased production of red blood cells. At this date it is not yet known why the disease develops. Secondary absolute polycythemia occurs from an increase in erythropoietin, a hormone that regulates red blood cell production; this condition can develop as a result of heart disease or heart failure, or as a result of problems within the kidneys themselves.