On the net I found the RDA for Vitamim B-12 for humans is 6 mcg.

On the net I also found the RDA for Vitamin B-12 for canines to be
0.022 mg/kg. My dog weighs about 8 kg so he would need
0.22 mg/kg * 8 kg which equals about 0.18 mg of B-12 per day. Now .18 mg is
equivalent to 180 mcg.

Suppose the average human weighed 150 lbs or about 68 kg. So,
such a person ought to get 6 mcg/day, but a much smaller dog at 8 kg is
supposed to get 180 mcg/day according to the calcuations above.

Thanks for your help.

--Marshall