Intestinal Cobalamin Malabsorption (Discovered in the Komondor)

Intestinal Cobalamin Malabsorption (ICM) or Imerslund-Gräsbeck Syndrome is a disorder where the body is unable to absorb cobalamin (vitamin B12) in the small intestine. This results in weakness and failure to thrive, vomiting, diarrhea, anemia, and decreased numbers of white blood cells (immune system cells).

Key Signs

Failure to thrive, Weakness, Anemia, Neutropenia, Loss of appetite, Vomiting, Diarrhea, Proteinuria

Age of Onset

0 to 2 yrs

Juvenile onset


Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with ICM

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about ICM

Clinical signs of intestinal cobalamin malabsorption (IGS) can be seen in puppies 6 to 12 weeks of age, when cobalamin stores become depleted. Puppies with IGS suffer from weakness and loss of appetite and fail to grow normally. Bloodwork shows anemia, neutropenia, and low cobalamin concentrations. Proteinuria is typically present. High levels methylmalonic acid can also be observed in the urine. All clinical signs and metabolic abnormalities, except proteinuria, are reversed by regular parenteral cobalamin administration. The proteinuria appears to be benign having no effect on long term health

Treatment consists of lifelong parenteral supplementation of cobalamin (vitamin B12). Regular injections of cobalamin, typically every 2-4 weeks, provide rapid resolution and control of clinical signs. A sublingual spray of vitamin B12, administered daily, has also been used with success.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to occur. A carrier dog with one copy of the ICM mutation can be safely bred with a clear dog with no copies of the ICM mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the ICM mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the ICM mutation could develop due to a different genetic or clinical cause.

Technical Details

Variant G>A
Chromosome 2
Coordinate 19,981,457

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Fyfe, J. C., Hemker, S. L., Frampton, A., Raj, K., Nagy, P. L., Gibbon, K. J., & Giger, U. (2018). Inherited selective cobalamin malabsorption in Komondor dogs associated with a CUBN splice site variant. BMC Veterinary Research, 14(1), 1–10. View the article