Unlike Vitamin A and D which is fat soluble, Vitamin B12 is water soluble. This means that it dissolves in water and is excreted from the body daily, so it needs to be replenished regularly. Vitamin B12 is found naturally in animal products such as meat, poultry, fish, and eggs. It is also added to some fortified foods like cereals and soy milk.
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What is Vitamin B12?
Dogs are dependent on nutrition to obtain cobalamin, a cobalt-containing compound also known as vitamin B12. Cobalamin is an important nutrient that helps keep the nervous system functioning properly, aids in the production of red blood cells, and helps metabolism run smoothly.
Vitamin B12 deficiency in dogs is more common than deficiency of other Vitamins such as Vitamin A but there is something worth noting about B12. Malabsorption (the inability to properly absorb nutrients) of cobalamin is the most common cause of B12 deficiency in dogs. This means that even if your dog is eating a well-balanced diet, they may still be lacking in this important nutrient.
Cobalamin Metabolism in Dog’s Body
Cobalamin is bound to the transport protein haptocorrin and carried to the small intestine for absorption after being taken in. Haptocorrin is also known as R-protein or transcobalamin I. In the small intestine, cobalamin is released from haptocorrin by pancreatic enzymes and binds to intrinsic factor (IF). Intrinsic factor is a glycoprotein synthesized in the stomach that is necessary for cobalamin absorption.
After binding to intrinsic factor, cobalamin is absorbed by active transport across the ileum (the last portion of the small intestine) and enters the circulation bound to plasma proteins. In circulation, most cobalamin is bound to haptocorrin (also known as transcobalamin II or TCII). A small amount of cobalamin (about 10%) is bound to serum albumin.
Cobalamin is stored in the liver and other tissues, primarily in its active form, methylcobalamin. Methylcobalamin is required for methionine synthase activity. Methionine synthase catalyzes the conversion of homocysteine to methionine. Methionine is required for protein synthesis and S-adenosylmethionine (SAMe) formation. SAMe is a methyl donor involved in numerous biochemical reactions, including DNA and RNA methylation.
Vitamin B12 Deficiency in Dogs: Causes and Symptoms
The most common cause of vitamin B12 deficiency in dogs is malabsorption. This can be due to a variety of reasons, including:
Inflammatory bowel disease:
Inflammatory bowel disease (IBD) is a condition in which the lining of the gastrointestinal tract becomes inflamed. IBD can lead to malabsorption of nutrients, including vitamin B12.
Exocrine pancreatic insufficiency:
Exocrine pancreatic insufficiency (EPI) is a condition in which the pancreas does not produce enough enzymes to properly digest food. This can lead to malabsorption of nutrients, including vitamin B12.
Bacterial overgrowth is a condition in which there is an overgrowth of bacteria in the gastrointestinal tract. This can lead to malabsorption of nutrients, including vitamin B12.
In some cases, vitamin B12 deficiency may be due to a diet that is lacking in this nutrient. This is more common in vegetarian or vegan dogs, as animal products are the best source of vitamin B12.
Symptoms of vitamin B12 deficiency in dogs can vary depending on the severity of the deficiency. In mild cases, symptoms may be barely noticeable. However, in severe cases, vitamin B12 deficiency can lead to anemia and neurological problems.
Conditions associated with Cobalamin deficiency
There are a few known genetic defects that can lead to cobalamin malabsorption and/or deficiency. These include:
Imerslund-Grasbeck syndrome is a condition that affects the absorption of cobalamin in the gastrointestinal tract. Dogs with this condition are unable to properly
Common symptoms of vitamin B12 deficiency in dogs include:
Dogs with vitamin B12 deficiency may seem tired or lethargic.
Loss of appetite:
Dogs with vitamin B12 deficiency may lose their appetite or be picky eaters.
Dogs with vitamin B12 deficiency may lose weight, even if they are eating a normal diet.
Dogs with vitamin B12 deficiency may have diarrhea.
Dogs with vitamin B12 deficiency may vomit.
Dogs with vitamin B12 deficiency may seem weak or unsteady on their feet.
Vitamin B12 deficiency can lead to a build-up of homocysteine in the blood. This is known as hyperhomocysteinemia. Homocysteine is an amino acid that is normally metabolized by vitamin B12. If there is a vitamin B12 deficiency, homocysteine can build up and cause damage to blood vessels, which can lead to stroke or heart disease.
Vitamin B12 deficiency can lead to anemia. Anemia is a condition in which the blood is unable to properly transport oxygen to the body’s tissues. This can cause symptoms such as fatigue, weakness, and shortness of breath.
Other symptoms of Vitamin B12 deficiency are;
- Decreased appetite
- Weight loss
- Muscle wasting
- Ataxia (loss of coordination)
If you notice any of these symptoms in your dog, it is important to take them to the vet for a check-up. Vitamin B12 deficiency can be diagnosed with a blood test. Treatment for vitamin B12 deficiency will typically involve supplements or injections of vitamin B12. In severe cases, hospitalization may be necessary.
3 Ways to Diagnose Cobalamin deficiency:
Measuring a serum cobalamin level:
This is the most common test used to diagnose cobalamin deficiency. However, it is important to note that a low serum cobalamin level does not necessarily mean that there is a cobalamin deficiency. This is because the body can store cobalamin in the liver, so even if there is a cobalamin deficiency, the serum cobalamin level may not be low.
Measuring serum homocysteine levels:
This test is used to measure the levels of homocysteine in the blood. High levels of homocysteine can be a sign of cobalamin deficiency.
Measuring serum methylmalonic acid levels:
This test is used to measure the levels of methylmalonic acid in the blood. Methylmalonic acid is a by-product of cobalamin metabolism, so high levels of methylmalonic acid can be a sign of cobalamin deficiency.
Treatment of Cobalamin deficiency:
The treatment for cobalamin deficiency will depend on the cause of the deficiency. If the deficiency is due to a dietary deficiency, then treatment will typically involve supplements or injections of cobalamin. If the deficiency is due to a genetic defect, then treatment will typically involve lifelong supplementation with cobalamin.
Injections of cobalamin:
Cobalamin injections are the most common treatment for cobalamin deficiency. Cobalamin injections are typically given intramuscularly (into the muscle) or subcutaneously (under the skin).
Cobalamin supplements are available in pill form and can be given orally. However, it is important to note that cobalamin is not absorbed well from the gastrointestinal tract, so oral supplements may not be effective.
Lifelong cobalamin supplementation:
If the cobalamin deficiency is due to a genetic defect, then lifelong supplementation with cobalamin will be necessary. This typically involves injections or supplements of cobalamin.
In severe cases of cobalamin deficiency, hospitalization may be necessary. This is typically only necessary if the individual is experiencing serious symptoms such as seizures or coma.
Preventing Vitamin B12 Deficiency in Dogs
The best way to prevent vitamin B12 deficiency in dogs is to feed them a balanced diet that includes animal products. This is because animal products are the best source of vitamin B12. Vitamin B12 supplements may also be necessary for dogs that are unable to eat animal products or that have a genetic defect that prevents them from absorbing cobalamin.
Dose of Vitamin B12 to give your B12-deficient dog:
The following are Vitamin B12 dosages recommended by By Maureen Carroll, DVM, and DACVIM.
Vitamin B12 oral dosing for dogs:
For a body weight of 1–10 kg, give ¼ of a 1 mg tablet daily; for 10–20 kg, give half of a 1 mg tablet daily, and for >20 kg, give one tablet daily.
Vitamin B12 Subcutaneous dosing for dogs:
250-1200 µg once weekly for six weeks, followed by monthly administration based on cobalamin levels.
Best Food for dogs with B12 Deficiency:
- Zignature—Kangaroo Limited Ingredient Formula Grain-Free Dry Dog Food
- Cobalequin Dogs
- Nutrition Strength Vitamin B12 for Dogs Plus Folate & Calcium Support the Nervous System & Blood Cell Formation
- WonderLabs Pet Factor B-12 B-12
FAQs on Vitamin B12 Deficiency in Dogs:
Q: What are the symptoms of vitamin B12 deficiency in dogs?
A: The symptoms of vitamin B12 deficiency in dogs can vary depending on the severity of the deficiency. The most common symptom is anemia, which can cause fatigue, lethargy, and weakness. Other symptoms include weight loss, loss of appetite, and diarrhea. In severe cases, vitamin B12 deficiency can cause seizures and coma.
Q: What are the causes of vitamin B12 deficiency in dogs?
A: The most common cause of vitamin B12 deficiency in dogs is a dietary deficiency. This can occur if the dog is not eating enough animal products, which are the best source of vitamin B12. Other causes of vitamin B12 deficiency include a genetic defect that prevents the absorption of cobalamin, and certain medications that can interfere with cobalamin absorption.
Q: How is vitamin B12 deficiency diagnosed in dogs?
A: Vitamin B12 deficiency is typically diagnosed based on the symptoms and medical history of the dog. A blood test may also be performed to measure cobalamin levels.
Q: How is vitamin B12 deficiency treated in dogs?
A: The treatment for vitamin B12 deficiency will depend on the cause of the deficiency. If the deficiency is due to a dietary deficiency, then treatment will typically involve supplements or injections of cobalamin. If the deficiency is due to a genetic defect, then treatment will typically involve lifelong supplementation with cobalamin.