Pyruvate kinase deficiency is a hereditary hemolytic anemia that results from a decrease of the essential red blood cell enzyme pyruvate kinase (PK). This enzyme helps convert glucose to energy when oxygen is low. If the amount of the enzyme is low, the red blood cells break down more rapidly than usual, leading to hemolytic anemia. In late phases of the disease, the bone marrow becomes exhausted and may become scarred, which results in myelofibrosis. At this point, the anemia is terminal. The two other fatal complications of pyruvate kinase deficiency are osteosclerosis and liver failure.
The disease has been reported in the West Highland White Terrier, Cairn Terrier, Miniature Poodle, and other breeds of dogs and cats. The mode of inheritance in the Basenjis and Beagle is autosomal recessive, meaning that a dog must get the defective gene from both parents to develop the disorder. The age at detection of hemolytic anemia is between 6 months and 3 years.5 Diagnosis can be confirmed by measuring red cell PK levels. When the bone marrow of dogs with PK deficiency is transplanted with bone marrow from a normal dog, severe anemia is corrected and hepatic iron accumulation and cirrhosis are prevented. Transplanted dogs do not develop bone disease, a characteristic complication in untreated dogs.6
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Breeding plans can be managed through use of laboratory tests that can identify heterozygotes, although some overlap exists in the ranges for enzyme values between homozygote normal and heterozygote carriers. Genetic tests for pyruvate kinase deficiency are available through the University of Pennsylvania at PennGen, OptiGen and VetGen. OFA maintains a voluntary diagnostic service for Basenjis with pyruvate kinase deficiency in cooperation with national breed clubs.4
PK deficiency is described for the first time in three apparently unrelated West Highland white terriers from Ireland and the UK. All three dogs were diagnosed with markedly regenerative but persistent anemia and had been treated for presumed immune-mediated hemolytic anaemia before hereditary erythrocyte PK-deficiency was confirmed by breed-specific DNA mutation analysis.
- Alan H. Rebar. A Guide to Hematology in Dogs and Cats
- Nemi Chand Jain. Essentials of Veterinary Hematology
- Norman F. Cheville. Ultrastructural Pathology: An Introduction to Interpretation
- Debra Eldredge, Liisa D. Carlson, DVM, Delbert G. Carlson, James M. Giffin. Dog Owner's Home Veterinary Handbook
- Mary Anna Thrall, Dale C. Baker, E. Duane Lassen. Veterinary hematology and clinical chemistry
- James C. Barton. Hemochromatosis: genetics, pathophysiology, diagnosis and treatment
- Erythrocyte pyruvate kinase deficiency in three West Highland white terriers in Ireland and the UK