It is a water-soluble vitamin, but it is the only one that can be stored in the liver. Contains cobalt in its structure. It is necessary for the formation of red blood cells, the synthesis of DNA and the construction of myelin sheaths around the nerves [1]. To be absorbed from the intestines, it must bind to a protein transporter. Dogs produce it in the stomach and pancreas, and cats only in the pancreas (any pancreatic disease in a cat drastically cuts it off from the absorption of B12) [2].
What it contains: Only in products of animal origin: offal, fish, egg yolks and red meat.
Deficiency: Rarely results from the diet itself, most often it is associated with intestinal diseases (e.g. IBD) or pancreas. It leads to megaloblastic anemia (faulty, large blood cells), cachexia, diarrhea and neuropathy [3].
Excess: Because it is a water-soluble vitamin, its excess is efficiently removed with urine and poisoning does not occur.
Sources
- National Research Council (2006). Nutrient Requirements of Dogs and Cats - Chapter 6, Water-Soluble Vitamins. National Academies Press. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats
- Siani G, Mercaldo B, Alterisio MC, Di Loria A (2023). Vitamin B12 in Cats: Nutrition, Metabolism, and Disease. Animals 13(9):1474. https://doi.org/10.3390/ani13091474
- Kather S, Grützner N, Kook PH, Dengler F, Heilmann RM (2020). Review of cobalamin status and disorders of cobalamin metabolism in dogs. J Vet Intern Med. https://doi.org/10.1111/jvim.15638