Recognizing the symptoms of vitamin B12 deficiency in dogs is important if you suspect your dog may be predisposed to such deficiency. Among the various types of vitamins dogs need, vitamin B12 is one of the most important. Indeed it may be said that vitamin B12 is a vitamin that is essential to all dogs, so much so that a lack of it may cause various problems. Symptoms of vitamin B12 deficiency in dogs may not be readily recognized by dog owners but deficiencies can be readily detected through a quick blood test.
The Importance of Vitamin B12 in Dogs
Vitamin B12, also known as colabamine, plays an important role in ensuring the proper functioning of the dog's nervous system and proper cell growth. It also plays a relevant role in the formation of blood, healthy intestinal health and correct brain function.
This vitamin is found tightly bound to dietary animal-derived proteins. It is commonly found in fish, liver, meat, poultry, eggs and cheese.
In humans, in order to be readily absorbed, vitamin B12 found in protein needs to combine with intrinsic factor, a special protein secreted by the stomach. Afterward, it absorbed in the last portion of the small intestine, a location known as the ileum.
In dogs though, there is evidence that the intrinsic factor is secreted by the dog's pancreatic acinar cells and then is absorbed into the intestinal epithelial cells. At this point, the vitamin B12 separates from intrinsic factor and is released into the circulation. Vitamin B12 is stored in the liver and the kidney, where it's released as needed.
Since vitamin B12 is found in meat, particularly organ meat, because of a dog's meat-based diet, it is unusual for dogs to have a deficiency of such a vitamin. When dogs develop a vitamin B12 deficiency, it is therefore more likely to be caused by some problem with the ability of the dog's body in absorbing it.
Causes of Vitamin B12 Deficiency in Dogs
While a dog's stomach mostly acts as storage unit and churning machine, the dog's small intestine is responsible for absorption of important nutrients, and included among these is vitamin B12. Conditions causing the small intestine to become inflamed, thickened and excessively motile, may therefore cause problems with nutrient absorption and may cause lowered levels of vitamin B12, a condition medically referred to as hypocobalaminemia.
Conditions causing maldigestion or malabsorption problems such as inflammatory bowel disease (IBD), intestinal bacterial overgrowth (SIBO), exocrine pancreatic insufficiency (EPI) and hereditary selective cobalamin malabsorption found in certain dog breeds such as giant schnauzers, border collies, beagles, Chinese Shar Pei and Australian shepherds. In the Chinese Shar pei in particular, an abnormality was found specifically on chromosome 13.
The presence of intestinal parasites may also play a factor in a vitamin B12 deficiency in dogs, considering that a heavy parasite load may deprive the dog from important nutrients. In cases of long-term administration of antiacids, the antacids may also play in vitamin B12 deficiency in dogs inhibiting its proper absorption.
"In dogs and cats the most common causes of cobalamin deficiency are chronic and severe small intestinal disease and EPI. A recent study has shown that 82% of dogs with EPI were cobalamin deficient."~Dr. Jörg M. Steiner, board-certified veterinarian
Symptoms of Vitamin B12 Deficiency in Dogs
Vitamin B12 plays an important role in helping the proper absorption of iron, therefore dogs suffering from a deficiency may develop anemia. Signs of anemia in dogs are lack of energy and lethargy. Affected dogs may show little interest in activities such as playing or going for walks.
A vitamin B12 deficiency in dogs often shows up as a digestive disorder and it may be challenging to determine whether it's a cause or an effect of such deficiency. Affected dogs may have a history of vomiting diarhea and lack of appetite. Affected dogs may also have poor body condition and considerable difficulty gaining (or maintaining) weight.
Because vitamin B12 play an important role in correct brain function, a deficiency may cause in the affected dog cognitive changes such as confusion. Seizures may also be one of the symptoms of vitamin B12 deficiency in dogs.
Nowadays, B12 levels can be assessed with a special type of blood test that isn't commonly included in routine blood tests. Texas A&M University offers testing of blood samples for the detection of lowered levels of serum Cobalamin (Vitamin B12) and (MMA) concentration of serum or urine for the detection of Cobalamin deficiency at a cellular level.
Treatment of Vitamin B12 Deficiency in Dogs
Dogs suffering from vitamin B12 deficiency may not respond to treatment for the underlying gastrointestinal disorder until vitamin B12 is replenished. The ideal route of B12 administration is by subcutaneous injection.
Oral supplementation is generally not metabolized well and therefore may not provide much benefit in dogs suffering from malabsorption states (e.g. pancreatic disease).
Affected dogs are given B12 injections for several weeks, then every two weeks and then once a month. Dog owners can be instructed by their vet on how to give them at home. Levels of vitamin B12 should afterward be rechecked to determine whether B12 levels are back to ideal levels.
When warranted, and advised by a veterinarian, oral administration of vitamin B12 can be given to affected dogs. Oral cobalamin should be given for a total of 12 weeks with a recheck for serum cobalamin concentration levels one week afterward.
According to Texas A&M University, Department of Small Animal Clinical Sciences the doses of B12 for dogs may range from 250 to 1000 µg depending on size. Dogs under 20 pounds are usually given 250µg, dogs 20 to 40 pounds are given 500 µg and dogs over 40 pounds are given 1000µg.
Vitamin B12 is water soluble and this means that if this vitamin is ingested in excess it may simply be flushed out through urination. Dogs should be allowed access to plenty of fresh water at all times.
"We currently recommend that all dogs and cats with chronic histories of gastrointestinal disease should have serum cobalamin concentration measured. As cobalamin is inexpensive, water soluble and any excess is readily disposed, cobalamin supplementation should certainly be considered for any animal with a serum cobalamin concentration lower than the laboratory reference range."~Texas A&M
- DVM360: Cobalamin: Don't leave home without it (Proceedings)
- Texas A&M University, Cobalamin: Diagnostic use and therapeutic considerations