Cobalamin is the most complex vitamin and the only one that dogs can obtain solely from meat products. Every plant-based form of vitamin B12 is an antagonist of cobalamin, meaning it acts as an inhibitor or counteragent. These are also known as pseudo-vitamin B12.
Cobalamin is essential for the production of blood cells, white blood cells, and nerve cells, as well as for the body’s own formation of folic acid. A deficiency in vitamin B12 is rare but not unheard of and is often associated with digestive disorders or pancreatic diseases.
Main Effects
- needed for the production of renewable cells such as white, red, and nerve cells
- involved in the conversion of homocysteine to methionine
- participates in the catabolism of branched-chain amino acids (BCAA)
Main Sources
- meat and organs
- fish
Requirement
- NRC: 1.15 µg/kgME
- FEDIAF: 3.5 µg/100 gDM
Vitamin B12 is water-soluble, but it still requires its own carrier to pass through the intestinal wall. In dogs, the pancreas secretes an intrinsic factor, which is a protein that binds to vitamin B12. In humans, the intrinsic factor is secreted from the stomach, but in dogs, the intrinsic factor secreted by the stomach is insignificant. In cats, the intrinsic factor is secreted only by the pancreas. This complex moves through the intestinal wall at the end of the small intestine.
Since vitamin B12 cannot absorb on its own, the reason for a deficiency when the diet provides enough vitamin B12 is the lack of intrinsic factor. Another important reason is intestinal inflammation.
In dogs, the most common cause of this is pancreatic insufficiency or chronic pancreatitis. A long-term infestation of the broad tapeworm also causes vitamin B12 deficiency because the tapeworm efficiently utilizes the digested food in the intestine.
If a lot of plant-based products are used and too little meat or organs are given, vitamin B12 deficiency also occurs. The plant-derived form of vitamin B12 also binds to the intrinsic factor, preventing animal-derived vitamin B12, but it is not biologically active in the body. Veganism is not common in dogs but is unfortunately on the rise. If the owner does not ensure their dog’s intake of vitamin B12 as they do for themselves, a deficiency will eventually occur.
There is still a misconception that active vitamin B12 can be obtained from seaweed, sprouts, and tempeh, but this is not true. The only external source of vitamin B12 outside of meat products and bacterial activity is nori seaweed, but if it is dried, the vitamin B12 is destroyed.
Vitamin B12 deficiency develops slowly because, despite its water solubility, it has long-lasting stores, partly due to its slow metabolism. In humans, vitamin B12 is stored for 1 to 2 years, sometimes even up to four years. There is no certain information on the duration of stores in dogs, but it is probably less than a year due to dogs’ generally faster metabolism. This is supported by how quickly a dog develops deficiency symptoms, for example, due to pancreatic problems.
The clearest symptom of vitamin B12 deficiency is pernicious anemia, as new red blood cells do not form properly or sufficiently. In humans, rarer symptoms have included muscle weakness, infertility, and hyperpigmentation of the skin. The worst problems from a long-term deficiency, for example in the nervous system, do not improve even if intake is restored.
Vitamin B12 is also needed for the conversion of homocysteine to methionine. It is also involved in protein metabolism, as without vitamin B12, the breakdown, or catabolism, of branched-chain (BCAA) amino acids is not possible.
If a vitamin B12 deficiency is suspected, it can be determined by a blood test.