Disorder - Erythrocytosis

Organ Systems Involved
Cardiovascular

Alternative Names
Polycythaemia

Presenting Signs

Erythrocytosis is an abnormal increase in the concentration of circulating red blood cells (RBC). It can be called either relative or absolute.

Relative erythrocytosis occurs following dehydration and is a normal response to the loss of body fluid. Absolute erythrocytosis refers to increased production of red cells. This can be due to a disorder of the bone marrow that causes over-production of red cells (primary erythrocytosis). Primary erythrocytosis is a rare condition in the cat, and usually occurs due to a cancerous condition in the bone marrow. It can also be caused by an underlying condition that makes the bone marrow produce excess red cells. Conditions such as chronic lung disease, congenital heart disease, severe obesity, tumours, kidney disease or hormonal problems may cause this over-production (secondary erythrocytosis).

Cats with erythrocytosis may show symptoms such as increased redness of skin and gums, increased thirst and urination, bleeding from the nose, blood in the urine or faeces, vomiting blood, vomiting, diarrhoea, lethargy and loss of appetite. Other symptoms include central nervous signs like dementia, loss of ability to control muscular movement, blindness and seizures.

Treatment

Medical: absolute erythrocytosis is initially treated by removing blood and intravenously replacing with an equal amount of balanced fluids (phlebotomy) and removing the inciting cause. Chemotherapy using agents such as hydroxyurea may be required.

PubMed References
Erythrocytosis

Contributor
Valerie See