It is characterized as a deficiency in the Phosphofructokinase (PFK) enzyme throughout the body, including the skeletal muscles and red blood cells.

This type presents with exercise-induced muscle cramps and weakness (sometimes rhabdomyolysis), myoglobinuria, as well as with haemolytic anaemia causing dark urine a few hours later.

Survival rate for the infantile form of PFK deficiency is low, and the cause of death is often due to respiratory failure.

[citation needed] The defining characteristic of this form of the disorder is hemolytic anemia, in which red blood cells break down prematurely.

Most notably, PFK deficient dogs have mild, but persistent, anemia with hemolytic episodes, exercise intolerance, hemoglobinuria, and pale or jaundiced mucous membranes.

[citation needed] In order to get Tarui's disease, both parents must be carriers of the genetic defect so that the child is born with the full form of the recessive trait.

[citation needed] Phosphofructokinase is a tetrameric enzyme that consists of three types of subunits: PFKL (liver), PFKM (muscle), and PFKP (platelet).

[13] The mutation impairs the ability of phosphofructokinase to phosphorylate fructose-6-phosphate prior to its cleavage into glyceraldehyde-3-phosphate which is the rate limiting step in the glycolysis pathway.

Dogs with the mutation display 10–20% of normal PFK activity in their erythrocytes, due to a higher proportion of PFKM in those cells.

The logic behind this treatment is that the low-carb high fat diet forces the body to use fatty acids as a primary energy source instead of glucose.

Mitapivat (brand name Pyrukynd) may improve symptoms by stimulating pyruvate kinase, another enzyme in the glycolytic pathway.

Owners are advised to keep their dogs out of stressful or exciting situations, avoid high temperature environments and strenuous exercise.

Dogs carrying the mutated form of the gene should be removed from the breeding population, in order to reduce incidence of the condition.