Pellagra results from a niacin (vitamin B3) deficiency and occurs in many mammals, including humans and dogs. While the symptoms are similar for dogs and people, canine pellagra is more commonly called blacktongue because it often causes darkening of a dog's tongue. Pellagra can be prevented through good nutrition and can be treated. In fact, dogs played an important role in the identification of the treatment used to treat human pellagra as well.
According to Shawn Messonnier, D.V.M., dogs need vitamin B3 for many reasons. One reason is that over four dozen enzymes require niacin to work properly. Niacin also helps dogs' circulatory system and keeps their skin healthy. Energy production, hormone synthesis, and metabolic processes require vitamin B3, as does a healthy nervous system. Dogs get their necessary supply of niacin in one of two ways. First, they can consume foods that contain niacin or its related nutrients. Second, they can consume tryptophan that their body can convert into niacin as long as they also have enough iron, riboflavin and vitamin B6.
The causes of canine pellagra and its human version can be traced back to the same culprit: a diet low in niacin and/or tryptophan. Niacin occurs naturally in milk, eggs, and beans while tryptophan can be found in many high protein foods, such as cheese, chicken, fish, peanut butter, soy and turkey. Dogs whose diets consist primarily of corn or corn products, however, can become niacin deficient. In fact, modern outbreaks of pellagra among humans occur primarily among people whose diets are corn based. To prevent the development of canine pellagra, dogs need to consume 11.4 mg/kg of niacin per day, according to the recommendations from the Association of American Feed Control Officials (AAFCO).
The symptoms of canine and human pellagra do not differ much. The three main symptoms of the condition include dermatitis, diarrhea and dementia. Dogs may also suffer from difficulty swallowing. Canine pellagra presents discolored patches on the dog's tongue. These patches are usually yellowish brown or black. Without treatment, canine pellagra can lead to death.
The best treatment for canine pellagra is niacin supplements. A researcher named Conrad Elvehjem used niacin supplements to cure dogs of the disease in 1937. Because the condition was so similar to pellagra in humans, the same treatment was tried with people who had the disease and, of course, it worked. Not only did discovery make pellagra treatable but also helped the medical community identify the cause of the condition as niacin deficiency.
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