B12 Methylcobalamin vs Hydroxocobalamin The difference between in clinic B12 injections vs over the counter. There are many forms of vitamin B12, the form used at La Bella is Methylcobalamin. The Can you buy ampules of vitamin B12 over the counter? Vitamin B 12 Injectable for Horses, Dogs and Cats 1000 mcg 250 ml Vitamin B 12 Injectable for Horses, Dogs and Cats Jeffers Compounded Hydroxocobalamin (Vitamin B12) Injection