Metabolic findings in the erythrocytes of cardiopathic and anaemic dogs

Few data are available on the activities of canine erythrocyte enzymes and on 2,3 diphosphoglycerate (2,3DPG) concentrations in pathological conditions other than heritable erythrocyte defects. Because some diseases might affect erythrocyte metabolism and oxygen transport, we evaluated these parameters in 10 healthy dogs and in dogs with symptomless dirofilariosis (n = 9), mild (n = 13) and severe (n = 8) cardiac failure, and haemolytic anaemia (n = 8). To evaluate possible membrane damage, the osmotic fragility of the red cells was measured. No haematological abnormalities were found in the dogs with mild cardiopathy or in those with symptomless dirofilariosis. Severe anaemia and neutrophilic leucocytosis were found in the dogs with haemolytic anaemia and, to a lesser degree, in those with severe heart failure. In dogs with these two diseases, elevated values obtained were, respectively: pyruvate kinase (PK) 17.5 ± 10.3 U/g haemoglobin (Hb) (P < 0.001) and 11.6 ± 7.5 U/g Hb (P < 0.01); glucose-6-phosphate dehydrogenase (G6PDH) 8.9 ± 5.4 U/g Hb (P < 0.001) and 5.6 ± 4.2 U/g Hb; 2,3DPG 21.8 ± 4.9 U/g Hb (P < 0.001) and 22.5 ± 4.1 U/g Hb (P < 0.001). The increased 2,3DPG concentrations may have been due to diminished oxygen availability but the observed enzymatic changes were attributed mainly to the presence of young red blood cells: there was a positive correlation between nucleated red blood cells and PK activity, G6PDH activity and 2,3DPG concentration and a negative correlation between mature erythrocytes and PK activity, G6PDH activity and 2,3DPG concentration. This was supported by the derivative curve of the fragiligram, which showed two or three peaks corresponding to different erythrocyte populations and by the negative correlation between the maximum haemolytic NaCl concentration and the reticulocyte number. The measurement of PK and G6PDH activity and of the 2,3PG concentration, together with information provided by the fragiligram would seem to be of value in defining the clinico-haematological picture in clinical heart diseases and haemolytic anaemia.