bac out cold or hot water Bac-Out Carpet Stain + Odor Remover Hot vs. Cold Water Therapy:
Description
High serum levels of homocysteine and low serum levels of B12 have been associated with reduced cognitive function

showed in the lab

If its not by eating plants, its with a mineral salt block left out for them
You should tailor a B12 supplement to meet your needs and not overdo it because the liver stores B12, and the kidneys send excess vitamin B12 out through urine