Pyruvate Kinase Deficiency

Pyruvate kinase deficiency is a hereditary hemolytic anemia that closely resembles human disease and 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. This destruction can result in hemolytic anemia, or too few oxygen-carrying red blood cells.

Breeds at Risk

The mode of inheritance in the Basenjis and Beagles 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 always less than 6 months, and usually less than 3 years. The disease has also been reported in West Highland White terriers, Cairn terriers, miniature poodles, and various other breeds of dogs and cats.⁵

The PK deficiency leads to impaired glucose utilization and consequently premature red cell destruction. In late phases of the disease, the bone marrow becomes exhausted and may become scarred leading to a a condition called myelofibrosis. At this point, the anemia is terminal.

Signs, Diagnosis & Treatment

Affected dogs are less tolerant of exercise than normal littermates. They usually die of myelofibrosis, osteosclerosis, or liver failure by 3 to 5 years of age. 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

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, and from OptiGen and VetGen. OFA maintains a voluntary diagnostic service for Basenjis with pyruvate kinase deficiency in cooperation with national breed clubs.⁴

References

1. Alan H. Rebar. A Guide to Hematology in Dogs and Cats
2. Nemi Chand Jain. Essentials of Veterinary Hematology
3. Norman F. Cheville. Ultrastructural Pathology: An Introduction to Interpretation
4. Debra Eldredge, Liisa D. Carlson, DVM, Delbert G. Carlson, James M. Giffin. Dog Owner's Home Veterinary Handbook
5. Mary Anna Thrall, Dale C. Baker, E. Duane Lassen. Veterinary hematology and clinical chemistry
6. James C. Barton. Hemochromatosis: genetics, pathophysiology, diagnosis and treatment

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