Pyruvate kinase deficiency (Labrador retriever type) is an inherited metabolic disease affecting Labrador retrievers. Affected dogs have insufficient activity of the pyruvate kinase Enzyme which breaks down glycogen for energy. Deficiency of this enzyme results primarily in easily damaged red blood cells (hemolysis). Affected dogs typically present between 4 months and 2 year of age with pale gums from decreased numbers of red blood cells (Anemia) and lethargy or exercise intolerance. Clinical findings during a veterinary exam include severe anemia, hardening of the bones, and an enlarged spleen and liver. While dogs can live for several years with this disease, they typically die from severe anemia or liver failure by 5 years of age.
Genetic testing of the PKLR gene will reliably determine whether a dog is a genetic Carrier of pyruvate kinase deficiency (Labrador retriever type). Pyruvate kinase deficiency (Labrador retriever type) is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of being a carrier of the PKLR gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Dogs that are not carriers of the mutation have no increased risk of having affected pups.
There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.
Inal Gultekin G, Raj K, Foureman P, Lehman S, Manhart K, Abdulmalik O, Giger U. Erythrocytic Pyruvate Kinase Mutations Causing Hemolytic Anemia, Osteosclerosis, and Secondary Hemochromatosis in Dogs. J Vet Intern Med. 2012 Jul-Aug;26(4):935-44.