Polycythemia in dogs with chronic hypoxic pulmonary disease

Prolonged tissue hypoxia caused by chronic pulmonary disease is commonly regarded as an important mechanism in the development of secondary polycythemia, but little clinical data are available to support this hypothesis.To study the prevalence and severity of erythrocytosis accompanying chronic hypoxic pulmonary disease in dogs.Forty-seven dogs with hypoxic chronic pulmonary disease, 27 dogs with nonhypoxic chronic pulmonary disease, and 60 healthy controls.Dogs with chronic pulmonary disease and chronic hypoxemia (partial pressure of arterial oxygen [PaORed blood cell parameters measured at the end of the hypoxemia period were within the laboratory reference range in most dogs. In chronically hypoxemic dogs, hematocrit (Hct) was increased in 4/47 (8.5%; 95% confidence interval [CI], 0-17) dogs, erythrocyte count (Erytr) was increased in 12/47 (26%; 95%CI, 13-38) dogs and hemoglobin concentration (Hb) was increased in 3/47 (6.4%; 95%CI, 0-14) dogs. No marked polycythemia (Hct ≥65%) was noted in any of the dogs. Red blood cell parameters were not associated with the severity of hypoxemia (correlation to PaOPolycythemia is uncommon, and usually mild if present, in dogs with chronic hypoxia caused by pulmonary disease.