What It Is:
Vitamin B12, also known as cobalamin, is a water soluble vitamin essential for normal digestion, nerve function, and red blood cell production. In cats, B12 is commonly supplemented when levels are low due to intestinal disease, chronic illness, or malnutrition.
B12 is often given by injection or oral supplement and plays a major role in helping cats with weight loss, poor appetite, and chronic diarrhea.
🐾 Common Uses
B12 supplementation is recommended for cats with:
- Inflammatory Bowel Disease (IBD)
- Chronic diarrhea or vomiting
- Weight loss
- Pancreatitis
- Triaditis
- Exocrine pancreatic insufficiency (EPI)
- Chronic kidney disease
- Liver disease
- General malabsorption issues
It may also be used in cats recovering from illness or poor nutrition.
🧪 How It Works
Vitamin B12 is absorbed in the last portion of the small intestine, called the ileum. Inflammation or damage to this area prevents proper absorption, leading to low B12 levels, which worsen digestive problems and overall health.
Supplementing B12 helps:
- Restore energy and appetite
- Improve digestion
- Support nerve and brain function
- Stimulate red blood cell production
- Promote better absorption of nutrients
Many cats feel noticeably better once their B12 levels are restored.
💊 Dosage and Administration
B12 can be given in injection or oral form. Your vet will determine the best method and schedule based on your cat’s condition.
Injectable B12 (most common):
- Given under the skin once a week for four to six weeks
- Followed by monthly maintenance if needed
- Usually done at home with small syringes
Oral B12:
- Often in the form of methylcobalamin, the active form
- May be used for mild deficiency or maintenance
- Given daily or every few days with food
Most cats tolerate both methods well. Injectable B12 is usually preferred for cats with severe digestive issues.
⚠️ Side Effects and Safety
Vitamin B12 is very safe and side effects are rare. Because it is water soluble, excess amounts are excreted in the urine and do not build up in the body.
Possible minor side effects include:
- Mild soreness at the injection site
- Slight behavioral change after the injection due to increased energy
- Occasional vocalization during injection
If using an oral product, avoid those with artificial sweeteners or additives.
🩺 Monitoring and Follow Up
Your vet may monitor B12 levels using a serum cobalamin test to guide supplementation. Blood tests may be repeated after the initial treatment course to determine if continued supplementation is needed.
Many cats require ongoing maintenance dosing, especially if they have chronic IBD or pancreatic disease.
💡 Cat Owner Note
Low B12 is one of the most overlooked reasons cats lose weight or seem tired. A tiny shot once a week can make a huge difference in appetite, digestion, and energy. If your cat has chronic stomach or intestinal issues, ask your vet if B12 might help.
❓ Frequently Asked Questions About B12 for Cats
How do I know if my cat needs B12?
Signs include weight loss, diarrhea, vomiting, poor appetite, and lethargy — especially in cats with IBD or chronic illness.
Is injectable B12 better than oral?
For cats with digestive problems, injections work better because they bypass the gut. Oral supplements may work for mild cases or maintenance.
Can I give B12 at home?
Yes. Most owners give subcutaneous injections at home. Your vet will show you how.
How quickly does B12 work?
Some cats improve within a few days. Others may take several weeks to regain weight and energy.
Is B12 safe for long term use?
Yes. It is non toxic and safe to give as long as your vet recommends it.
What kind of B12 should I use?
Methylcobalamin is the preferred form, especially for oral use. Cyanocobalamin is often used in injections.