J. Comp. Path. 2000, Vol. 122, 25–34 Article No. jcpa.1999.0339, available online at http://www.idealibrary.com on Haematological Parameters and Altered Erythrocyte Metabolism in Anaemic Dogs S. Paltrinieri, S. Comazzi and F. Agnes Istituto di Patologia Generale Veterinaria, Via Celoria 10, 20133 Milano, Italy Summary In previous studies, an increase in the activity of pyruvate kinase (PK) and glucose-6-phosphate de- hydrogenase (G6PDH), an increase in the concentration of 2,3-diphosphoglycerate (2,3DPG), and al- terations in osmotic fragility were found in dogs with haemolytic anaemia. These changes were mainly caused by the presence of immature red cells found in regenerative anaemias. In the present study, the same parameters were evaluated in dogs with different types of anaemia. The haematological patterns of 40 anaemic dogs were analysed to define the pathogenesis and the haematological features of each case. Non-regenerative anaemias could be attributed principally to chronic diseases and to the haemolysis that accompanies the early stages of canine babesiosis. Regenerative anaemias were mainly due to haemolysis, in some cases with an immune-mediated pathogenesis. PK activity was higher in regenerative than in non-regenerative anaemias, but G6PDH activity and 2,3DPG concentration increased in both types of anaemia. This suggests that PK activity is influenced by the presence of immature red cells, but the requirements for reducing compounds and oxygen are not dependent on the type of anaemia. Abnormalities in osmotic fragility were detected in haemolytic anaemias and in those non-regenerative anaemias in which reticulocyte percentage, but not reticulocyte production index (RPI), increased. The osmotic fragility could be used as an early indicator of erythrocyte regeneration.  2000 Harcourt Publishers Ltd and of the presence of immature red cells were Introduction evaluated by measuring the parameters that are During canine regenerative anaemia, there is an characteristic of RBC metabolism and of mem- increase in red blood cell (RBC) glycolysis and brane integrity in dogs with different types of an- in the pentose-phosphate pathway that produces aemia. The study included cases of both reducing compounds, as indicated by increases regenerative and non-regenerative anaemia be- in pyruvate kinase (PK) and glucose-6-phosphate cause, despite the lack of immature red cells, some dehydrogenase (G6PDH) activities, respectively metabolic alterations of RBCs have been reported (Smith and Agar, 1975). In these situations, the in non-regenerative anaemias (King et al., 1992; concentration of 2,3 diphosphoglycerate (2,3DPG), Rodriguez-Franco et al., 1994). In addition, to verify which diminishes haemoglobin oxygen affinity and their diagnostic value, the haematological patterns is produced during glycolysis (Harvey, 1989), also in the various diseases were examined. increases; in addition, changes in osmotic fragility are detectable (Paltrinieri et al. , 1998). All these changes may be due to a decrease in oxygen avail- Materials and Methods ability (Bersin et al. , 1993), but they are also strongly Animals related to the presence of immature red cells that are known to have a high PK activity and a high The study was based on 40 dogs (Table 1) which resistance to osmotic stress ( Jain, 1993). were referred to this Institute with signs of anaemia. Clinical diagnoses were confirmed by bone marrow In the present study, the influence of hypoxia 0021–9975/00/010025+10 $35·00  2000 Harcourt Publishers Ltd