In the meat and dairy industry, animals are often supplemented with Vitamin B12 due to modern farming practices that limit their natural intake. So people who eat animals are simply taking a Vitamin B 12 Injectable Solution VetOne Vitamin B Complex HP Injection PBS Animal Health Durvet Maxi B 1000 100 ml Vitamin B12 250 ml, 1000 mcg ml Vitamin B 12 for Animal Use Generic (brand may vary) Valley Vet Supply Safe.Pharmacy Vitamins