Feline Polycythemia: Welfare and Management

Key Facts

• Polycythemia can be relative (dehydration), secondary (hypoxia-driven), or primary (bone marrow neoplasm)
• Clinical signs include deep red mucous membranes, bleeding from mucosae, seizures, and behavioral changes
• Secondary polycythemia from chronic hypoxia (heart disease, lung disease, renal tumors) is most common in cats
• Treatment depends on cause: phlebotomy provides immediate relief; hydroxyurea manages primary polycythemia
• Cats with polycythemia have blood that is too thick to flow normally, impairing oxygen delivery paradoxically

Welfare Considerations

Polycythemia causes welfare suffering through blood hyperviscosity: tissues are deprived of adequate oxygen because the blood is too thick to circulate efficiently. Neurological signs including circling, blindness, and seizures cause significant distress. The paradox of having too many red blood cells but inadequate oxygen delivery is clinically important and welfare-relevant. Phlebotomy (blood removal) provides rapid symptomatic relief and should be performed promptly when the packed cell volume exceeds 0.65. Long-term welfare depends entirely on identifying and managing the underlying cause.

What You Can Do

• Seek veterinary evaluation immediately for a cat with red-purple gums, neurological signs, or unexplained lethargy
• Agree to phlebotomy as an immediate welfare intervention — it provides rapid relief from hyperviscosity symptoms
• Investigate the underlying cause thoroughly — secondary causes are often treatable
• Monitor packed cell volume regularly during treatment to guide phlebotomy frequency
• Manage concurrent conditions (heart disease, lung disease) that drive secondary polycythemia