Abstract
Pathological and etiological features were examined clinicopathologically in cases of canine dirofilarial hemoglobinuria. Dogs suffering from serious filariasis without hemoglobinuria, as well as normal healthy dogs, were used as controls. This disease is frequent in male dogs 3 years or more of age. Its incidence is high in February, March and April. Direct Coombs' test was negative in 5 cases of hemoglobinuria. Groups of serious filariasis and hemoglobinuria showed an increase in osmotic and mechanical fragility of erythrocytes, characteristic poikilocytes, and mean corpuscular constants, suggesting hemolytic anemia, liver dysfunction, increase in free cholesterol level of serum, decrease in lecithin cholesterol acyltransferase activity, and hemosiderinuria. The latency of chronic intravascular hemolysis was also confirmed in the group of serious filariasis. The hemoglobinuria group differed significantly from this group. It showed filarial embolism in the venae cavae, marked acute liver dysfunction, increase in blood glucose and BUN levels, and increase in the α/total -β ratio of serum lipoproteins. In discussing the development of pathological features of dirofilarial hemoglobinuria, attention was paid to severe liver disturbances subsequent to congestion in the liver caused by embolism of the venae cavae with worms. The increased free cholesterol content of the serum lipoproteins was presumed to be an extracorpuscular hemolytic factor, the accompanying disturbances of cholesterol exchange in the erythrocyte membrane and the possible destruction of erythrocytes in a physical collision with worms were suggested to be rather direct causes of hemolysis.
