What is pyruvate kinase (PK) deficiency?
Pyruvate kinase deficiency in Basenji dogs is an inherited lack of an enzyme (pyruvate kinase) in the red blood cells of an affected animal. This enzyme is required for red blood cells to survive for a normal length of time in the blood of the animal, and when it is missing, the red blood cells break down and are destroyed prematurely. This leads to lifelong anemia in the affected animal. The symptoms of anemia are lack of energy, low exercise tolerance, easy fatiguability, and probably reduced fertility. This disease is inherited as an autosomal recessive.
This means that affected animals have two doses of the mutant gene. Dogs that have one mutant and one normal gene are called carriers. Carriers are not ill (they do not have anemia), but can produce affected offspring if mated to another carrier. Based on research conducted at Michigan State University and the University of Michigan leading to the discovery of the mutation causing PK in Basenjis, VetGen is proud to exclusively offer a non-invasive, highly reliable DNA-based test to detect PK.
How is PK deficiency inherited?
This is an autosomal recessive trait which means both parents of an affected dog are carriers of the disorder. Carriers have about one half normal enzyme activity in red blood cells, and are clinically unaffected.
What breeds are affected by PK deficiency?
This disorder occurs most commonly in Basenjis and has also been seen in West Highland white terriers, Cairn terriers and beagles.
For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have only listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.
What does PK deficiency mean to your dog & you?
Dogs with PK deficiency usually show signs by 4 months to 1 year of age. Because of the severe anemia (low levels of red blood cells), affected dogs are slow to grow, and show a mild weakness and a low tolerance for exercise.
Unfortunately these dogs also gradually develop changes in their bones, specifically replacement of the bone marrow with fibrous tissue, and hardening or abnormal density of bone (called myelofibrosis and osteosclerosis). Dogs with pyruvate kinase deficiency usually die before 4 years of age, due to bone marrow failure and/or liver disease.
How is PK deficiency diagnosed?
Signs of anemia include pale mucous membranes (your dog's gums for example), an increased heart rate and a reduced tolerance for exercise. Your veterinarian will do blood tests to determine the cause of the anemia which in this disorder is due to increased red blood cell breakdown. Further tests will be required to diagnose this specific condition as the cause of the hemolytic anemia.
How is PK deficiency treated?
There is no specific treatment for this disorder, other than removal of affected and carrier dogs from the breeding population.
Breeding advice
Because this is an autosomal recessive trait, both parents of affected dogs carry the defective gene. Neither affected (homozygous) or carrier dogs (heterozygous) should be used for breeding. There is a DNA test that can identify carrier dogs at any age (see reference below). Many affected and carrier dogs have already been removed from the breeding population.
VetGen have a test
This test provides breeders and owners a definitive diagnosis whether their dog is PK "Affected", "Carrier", or "Clear". With this information in hand, Basenji breeders and owners have key insight into their bloodstock and can proceed to make informed decisions about training, showing, and breeding plans for each dog.
Source: The Merck/Merial Manual for Pet Health, VetGen
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