Polycythemia, more precisely called erythrocytosis, is a PCV, red cell count and hemoglobin concentration above the reference interval. In dogs it is usually a sign of something else: dehydration, a right-to-left cardiac shunt or an erythropoietin (EPO)-secreting tumor. Primary polycythemia (polycythemia vera) is rare and is diagnosed only after those causes are excluded. Once the PCV climbs past about 60%, thick blood can cause seizures, bleeding and blindness, so recognising the cause quickly and lowering the PCV safely matter.
Key facts
Polycythemia at a glance- Species: dog (also reported in cats, horses and ferrets).
- System: hemic and lymphatic.
- Terminology: erythrocytosis means more red cells; "polycythemia" is used as a synonym but can imply that white cells and platelets are also increased, which is rare in dogs.
- Causes: relative (dehydration, splenic contraction) or absolute; absolute is primary (polycythemia vera) or secondary (hypoxia-driven, inappropriate EPO production, or other hormones).
- Classic presentation: a well-hydrated dog with brick-red mucous membranes, neurologic signs or bleeding, and a PCV well above 60% with normal total protein.
- Treatment: phlebotomy with fluid replacement, hydroxyurea for long-term control of primary disease, and correction of the cause where possible.
What's inside
12 sections in the full guide- Key facts
- How the NAVLE tests this
- Cause and pathophysiology
- Clinical signs
- Diagnosis
- Differential diagnoses
- Treatment and management
- Prevention and control
- Prognosis
- Quick review
- Test yourself
- References
The full guide also has 4 tables, 2 figures, 3 self-test questions and 18 references, available to NAVLE members.
Read the full study guide
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