Under normal conditions, vitamin B12 binds to specific proteins in the digestive tract and is absorbed in the small intestine with the help of a receptor-mediated process. In dogs affected by Imerslund–Gräsbeck Syndrome, a mutation disrupts the function of receptors responsible for transporting vitamin B12 into the bloodstream. As a result, even if dietary intake is adequate, the vitamin cannot be efficiently absorbed, leading to systemic deficiency.
Clinical signs of IGS-2 often appear in young dogs, typically after weaning when maternal vitamin B12 stores are depleted. Early symptoms may include poor growth, lethargy, reduced appetite, weight loss, and general weakness. As the deficiency progresses, affected dogs may develop anemia, pale gums, digestive disturbances such as diarrhea, and increased susceptibility to infections. Neurological signs may also occur due to impaired nerve function, including weakness, unsteady gait, and in severe cases, seizures or behavioral changes.
If left untreated, Imerslund–Gräsbeck Syndrome can become life-threatening due to severe anemia and metabolic dysfunction. However, with early diagnosis and appropriate management—particularly regular vitamin B12 supplementation—affected dogs can often lead healthy and active lives.
The IGS-2 DNA Health Test is designed to detect the specific genetic mutation associated with this condition. Testing is simple, safe, and non-invasive, typically requiring a cheek swab or blood sample. The collected sample is analyzed in a specialized laboratory to determine the dog’s genetic status. Since DNA remains unchanged throughout life, testing can be performed at any age, including in puppies before clinical signs develop.
Results are generally reported in three categories:
- Clear (Normal): The dog does not carry the IGS-2 mutation and cannot pass it to offspring.
- Carrier: The dog carries one copy of the mutation but typically does not show clinical signs. However, it can pass the mutation to future generations.
- Affected/At Risk: The dog carries two copies of the mutation and has a high likelihood of developing vitamin B12 absorption deficiency associated with Imerslund–Gräsbeck Syndrome.
Genetic testing for IGS-2 is highly valuable for breeders, veterinarians, and dog owners. Breeders can use test results to make informed mating decisions that help reduce or eliminate the mutation within breeding populations while maintaining healthy genetic diversity. Avoiding carrier-to-carrier matings significantly reduces the risk of producing affected puppies.
For dog owners, knowing a dog’s genetic status allows for early monitoring and preventive care. Dogs identified as affected can be effectively managed with regular vitamin B12 injections or supplementation, preventing most clinical complications if started early. Routine veterinary monitoring helps ensure proper growth, energy levels, and neurological health.
The Imerslund–Gräsbeck Syndrome (IGS-2) Health Test is a reliable genetic screening tool that supports responsible breeding practices, promotes canine metabolic health, and helps reduce the impact of this inherited vitamin absorption disorder in future generations.
