Spurious hyperbicarbonatemia and a negative anion gap in a cat and a dog with severe rhabdomyolysis.

A 3-year-old male neutered domestic shorthair cat and a 2-year-old male neutered Labrador-mix dog were separately presented to the Veterinary Medical Center for evaluation after sustaining significant muscle trauma due to a dog attack and seizure activity, respectively. In both cases, biochemical analysis was consistent with rhabdomyolysis. Additionally, a markedly increased measured serum bicarbonate concentration and negative calculated anion gap were observed. As these biochemical abnormalities were not expected and deemed incompatible with life, an interference with the analyzer measurement of bicarbonate involving marked increases in pyruvate and lactate dehydrogenase (LDH) following myocyte injury was suspected. Venous blood gas analysis calculated bicarbonate concentration and anion gap were within reference interval, while measured LDH activity was markedly increased. These findings supported an analyzer-generated interference. This is the first published report of a previously described chemistry analyzer interference of markedly increased LDH activity with serum bicarbonate concentration measurement in dogs and cats. Awareness of this interference is important, particularly in the emergency setting, as it may influence case management.