VetOne Vitamin B Complex HP Injection Features & Benefits High potency supplemental source of B complex vitamins in cattle, swine and sheep Overview Contains 100 mg B1, 5 mg B2, 100 mg niacinamide, 10 mg B6, 10 mg d-panthenol and 100 mcg B12
Scientific References Hydroxocobalamin 1mg/ml Solution for Injection SmPC (emc)
Dietary gaps, absorption problems, and age-related changes are incredibly common culprits behind a B12 shortfall
specific study formulations fall outside the scope of this discussion
Like Gambit62 said, a midwife might be able to provide solid answers
Alternatively, if the vial has positive pressure, pushing water in becomes difficult because you are compressing the air inside