Under normal conditions, vitamin B12 is absorbed in the small intestine through a specialized receptor-mediated process involving intrinsic factor and specific transport proteins. In dogs with IGS, a mutation—commonly affecting genes involved in cobalamin transport such as CUBN or related pathways (breed-dependent)—prevents proper absorption of vitamin B12. As a result, even dogs eating a normal diet may develop severe deficiency over time.
Clinical signs of IGS typically appear in young dogs, often after weaning or during early growth stages. Early symptoms may include poor appetite, reduced growth rate, lethargy, and general weakness. As vitamin B12 deficiency progresses, more serious signs develop, including weight loss despite normal eating, chronic diarrhea, vomiting, and failure to thrive.
One of the most important consequences of IGS is megaloblastic anemia, a condition where red blood cells are abnormally large and ineffective at carrying oxygen. This can lead to pale gums, weakness, exercise intolerance, and rapid fatigue. In some cases, neurological signs such as incoordination or behavioral changes may also occur due to the role of vitamin B12 in nerve function.
The IGS DNA Health Test is designed to detect the specific genetic mutation responsible for Imerslund–Gräsbeck Syndrome. The test is simple, safe, and non-invasive, typically performed using a cheek swab or blood sample. The collected DNA is analyzed in a specialized laboratory to determine whether the dog carries zero, one, or two copies of the mutation. Because genetic information remains unchanged throughout life, testing can be performed at any age, including before clinical signs develop.
Results are generally reported as:
- Clear (Normal): The dog does not carry the IGS mutation and is not expected to develop or pass on the disease.
- Carrier: The dog carries one copy of the mutation but is typically unaffected. However, it can pass the mutation to offspring.
- Affected/At Risk: The dog carries two copies of the mutation and is expected to develop vitamin B12 malabsorption and related clinical signs.
Genetic testing for IGS is highly valuable for breeders, veterinarians, and dog owners. Breeders can use results to prevent carrier-to-carrier matings, helping reduce the prevalence of this metabolic disorder in future generations while maintaining healthy genetic diversity within the breed.
For dog owners, early identification allows for prompt management of vitamin B12 deficiency. While there is no permanent cure for the genetic defect, affected dogs can be effectively managed with regular vitamin B12 supplementation, either through injections or oral therapy, which often leads to significant clinical improvement. Lifelong monitoring is typically required.
The Imerslund–Gräsbeck Syndrome (IGS) Health Test is a reliable genetic screening tool that supports responsible breeding practices, promotes canine metabolic and hematological health, and helps reduce the impact of this inherited vitamin absorption disorder in future generations.
