Dogs and cats must obtain vitamin B12 from their diet. Pet food (either in nature or commercial pet food) usually has adequate vitamin B12 and deficiency only happens if it is not being absorbed in the gut.
Vitamin B12 deficiency is common in dogs and cats with several diseases, including:
inflammatory bowel disease
exocrine pancreatic insufficiency
short bowel syndrome (especially where there has been bowel removed)
genetic B12 deficiency (reported so far in Shar Peis, Giant Schnauzers, Border Collies, and Beagles)
What causes B12 deficiency?
The suggested mechanisms of B12 deficiency in dogs with chronic GI disease are:
damage to the intestinal mucosal receptors needed for the binding of B12 complexes, or
An imbalance of “healthy” bacteria in the small intestine, leading to a decrease in the amount of B12 available for absorption.
There are also cases of hereditary B12 deficiency caused by gastrointestinal B12 malabsorption. Gene mutation causes the absence or malfunction of the receptor in the small intestine that binds the B12 complex.
What are the consequences of B12 deficiency?
They include inappetance, lethargy, failure to thrive, chronic diarrhoea , vomiting, neurological signs including seizures
The estimated biological half-life of B12 in dogs is 50-100 days, whereas in humans it is 330-400 days. So the total body stores of B12 are exhausted rapidly in dogs.
Chronic gastrointestinal diseases of whatever cause may not be responsive to otherwise-appropriate treatment UNTIL the B12 levels are normalized.
This is a super-important point: The B12 deficiency itself causes malabsorption. So even if vets are treating for a range of gastrointestinal problems, you won’t see a great response until you fix the B12 deficiency.
Treatment with B12 is simple and cheap. It can be administered with weekly injections (often by the owner at home). A new study has found that oral medication is also effective. Ask your vet for further information.