Protecting Your Furry Friend – Understanding Vitamin B12 Toxicity in Dogs

B12 is a water-soluble vitamin essential for forming red blood cells, nervous system function, and DNA synthesis. It also promotes gastrointestinal health and boosts appetite.

Animal-based foods such as beef liver, fish, and eggs naturally contain it. Certain conditions, such as gastrointestinal disease, can reduce the ability to absorb this vital nutrient.


Unlike other vitamins, B12 does not store in the body and must be consumed regularly or in a supplement. It is a vital water-soluble vitamin involved in several essential biological functions, such as the formation of red blood cells, amino acid metabolism, DNA synthesis, and neurological function.

A deficiency in vitamin B12 toxicity in dogs can result from a poor diet or gastrointestinal disorders that affect absorption. Certain dog breeds may also have difficulty absorbing the nutrients.

One of the most common symptoms of a deficiency is loss of appetite. If your dog eats less than usual or is uninterested in food, consult your veterinarian.

Your pet’s vet may prescribe a B12 injection or pill. Cyanocobalamin and methylcobalamin are two forms of the vitamin available. Your veterinarian will help you determine which supplement is best for your pet and how often it should be administered.


A diet rich in vitamin B12 is the best way to ensure your dog gets enough of this crucial nutrient. Beef liver is an excellent source of this vitamin, but it should be fed only in moderation due to its high concentration of vitamin A (which can lead to toxicity). Salmon is also a good source of vitamin B12, protein, and omega-3 fatty acids that promote skin and coat health. However, fish should be thoroughly cooked before being fed to dogs.

Often, a deficiency in vitamin B12 can be corrected with oral supplements. Cyanocobalamin is a standard treatment, as it is easily absorbed by the intestines and excreted into urine without accumulating in toxic levels. Your veterinarian will monitor your pet’s vitamin B12 levels and advise you of any changes in symptoms.

For severe deficiencies or malabsorption problems, your vet may recommend B12 injections. These are given under the skin and can be administered at home by a veterinarian.


A healthy dog diet is an excellent way to avoid vitamin B12 toxicity. The nutrient helps promote gastrointestinal health and nutrient absorption, which is critical to the body’s ability to absorb other vital nutrients. The nutrient is also essential in red blood cell formation and DNA synthesis.

Many factors can contribute to vitamin B12 deficiency, including diseases affecting the GI tract, such as exocrine pancreatic insufficiency and chronic pancreatitis. Dogs with gastrointestinal disorders like inflammatory bowel disease and intestinal parasites may have a reduced capacity to absorb nutrients.

A veterinarian will prescribe either oral B12 supplements or injectable cyanocobalamin as needed to get the pet’s blood levels up to standard. The vet will regularly test the dog’s blood until the acceptable level. In most cases, dogs prescribed supplemental B12 show signs of improvement within a few weeks. These symptoms include improved appetite, increased energy, better coat quality, and fewer gastrointestinal problems like diarrhea.


While a balanced diet is essential for your dog, routine veterinary exams and blood tests can help you identify potential issues like B12 deficiency at an early stage. It ensures your dog has a healthy metabolism and can absorb nutrients like cobalamin.

Cobalamin is also essential in the nervous system, helping create myelin that supports nerve cell function and allows your dog to control physiological functions like breathing and heart rate. Cobalamin can be found in foods such as meat (especially organ meats), fish, poultry, dairy products, and eggs.

While most dogs get enough B12 from their food, some breeds, like Giant Schnauzers, Border Collies, and Beagles, are genetically predisposed to gastrointestinal issues that make it difficult to absorb this nutrient. Pancreatic diseases like Exocrine Pancreatic Insufficiency, intestinal parasites, and bacterial overgrowth can also inhibit the ability to absorb this essential nutrient. For these reasons, it is recommended that all dogs receive a supplemental dose of cobalamin daily.