Pyruvate kinase (PK) is an enzyme critical to the anaerobic glycolytic pathway of energy production in the erythrocyte. If erythrocytes are deficient in PK they are unable to sustain normal cell metabolism and hence are destroyed prematurely. This deficiency manifests as an hemolytic anemia of variable severity with a strong regenerative response. In dogs, the anemia is always severe (PCV 10-20%).
The clinical signs of disease reflect the anemic status of the animal and include exercise intolerance, weakness, heart murmur and splenomegaly. The anemia is macrocytic, hypochromic and highly regenerative in dogs. Radiographs reveal generalized abnormalities in bone density including intramedullary mineralisation of the long bones suggestive of progressive osteosclerosis in dogs.