Cyanocobalamin (Vitamin B12)
Cyanocobalamin (Vitamin B12) is a water-soluble vitamin essential for normal cellular function, particularly in rapidly dividing cells. - **Primary Use**: Parenteral treatment of Vitamin B12 deficiency. - **Common Causes of Deficiency**: Exocrine pancreatic insufficiency (EPI), inflammatory bowel disease (IBD), and other malabsorptive gastrointestinal diseases. - **Species Specifics**: - **Dogs & Cats**: High prevalence of deficiency secondary to GI/pancreatic disease. Giant Schnauzers (and other breeds like Beagles and Border Collies) may have a genetic defect affecting cobalamin-intrinsic factor complex absorption (Imerslund-Grรคsbeck syndrome). - **Ruminants**: Deficiency is often secondary to dietary **cobalt** deficiency, as rumen microflora require cobalt to synthesize B12. > **Clinical Pearl**: Unlike humans, dogs and cats lack the cobalamin-binding protein TC1. This means they can rapidly deplete their B12 stores in just 1-2 months during states of malabsorption, whereas humans take 1-2 years.
Mechanism: Vitamin B12 acts as a crucial coenzyme for two major enzymatic pathways: 1. **Methylmalonyl-CoA mutase**: Converts methylmalonyl-CoA โ succinyl-CoA. (Deficiency leads to methylmalonic acidemia/aciduria). 2. **Methionine synthase**: Catalyzes the remethylation of homocysteine โ methionine, which is intimately linked with **folate** metabolism. - Required for normal cell growth, nucleoprotein and myelin synthesis, amino acid metabolism, and erythropoiesis. - **Note**: B12 deficiency can cause a functional folate deficiency. Unlike humans, macrocytic anemias do not appear to be a significant component of cobalamin deficiency in dogs or cats.
Dosing by species
- Treatment of vitamin B12 deficiency associated with cobalt deficiency (Lambs) ยท 100 micrograms (total dose) ยท injection ยท once weekly
- Treatment of vitamin B12 deficiency associated with cobalt deficiency (Adult sheep) ยท 300 micrograms (total dose) ยท injection ยท once weekly
- Treatment of vitamin B12 deficiency associated with cobalt deficiency ยท 0.2-0.4 mL of a 5000 micrograms/mL injection (1000-2000 micrograms) ยท IM or SC ยท weekly intervals if necessary
- Cobalamin deficiency in cats with IBD ยท 250-500 micrograms (total dose per cat) ยท SC ยท once per week for 6 weeks, then every 1-2 months
- Adjunctive treatment of idiopathic hepatic lipidosis ยท 250 micrograms (total dose) ยท SC ยท once per week ยท 6 weeks ยท Recheck serum B12 level in one to two weeks after cessation of treatment as some cats may need repeated administration.
- Cobalamin deficiency associated with GI disease ยท 150-250 micrograms (total dose) ยท SC ยท once weekly for 6 weeks, then every 14 days for 6 weeks, then one dose 30 days later ยท Initial 16-week protocol ยท Based on body size. Recheck serum cobalamin concentration one month after last dose.
- Cobalamin deficiency associated with exocrine pancreatic insufficiency ยท 100-250 micrograms (total dose) ยท SC ยท once weekly ยท Periodically assess cobalamin and folate levels.
- Treatment of vitamin B12 deficiency associated with cobalt deficiency ยท 0.2-0.4 mL of a 5000 micrograms/mL injection (1000-2000 micrograms) ยท IM or SC ยท weekly intervals if necessary
Routes of administration
Contraindications
- Hypersensitivity to cyanocobalamin or hydroxocobalamin
- Known hypersensitivity to cobalt or cobalamin
Adverse effects
- Pain at injection site (uncommon)
- Anaphylaxis (rarely reported in humans)
- Pain or stinging at the injection site
- Mild allergic reactions (rare)
Drug interactions
- Antibiotics ยท Concurrent use can cause falsely low serum or red blood cell cobalamin values if a microbiologic method assay is used.
- Omeprazole ยท May decrease oral absorption of Vitamin B12 by altering gastric pH ยท minor
Monitoring
- Serum cobalamin levels
- Serum folate status (both before and after treatment)
- Clinical signs associated with deficiency (weight loss, poor haircoat, vomiting, diarrhea)
- CBC (baseline and ongoing if abnormal)
- Serum cobalamin (Vitamin B12) levels
- Serum folate levels
- Clinical signs of gastrointestinal disease (weight gain, fecal consistency)
Overdose
Cyanocobalamin is very safe. An inadvertent overdose given via SC or IM injection is unlikely to cause significant morbidity.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.