How Vitamins Can Support Your Dog’s Health

by Lauren Samet
07/02/2019

We all know that vitamins help to keep our skin healthy, our eyes bright, and our hair shiny – and it’s just the same for dogs! In this guide we’re going to take a closer look at some of the crucial vitamins for your dog’s diet; covering everything from the roles they play in the body to the effects of a deficiency. 

Fat Soluble Vitamins

Vitamin A

Vitamin A is formed via the dietary precursors' retinol and beta carotene. Beta carotene is readily converted to vitamin A within the liver by a dog’s metabolism. It’s usually found in brightly coloured fruits and vegetables, such as carrots and peppers. Vitamin A is also found in the liver (including fish liver oil) and in egg yolks.

Roles: Vitamin A supports healthy vision, appetite, and skin and coat health. Natural beta carotenes also have an antioxidant effect. 
Deficiency: Signs include impaired vision, skin lesions, and occasionally abnormal bone growth.
Toxicity: Signs can include lameness and abnormal bone remodelling.
Vitapaws products found in: EyeWell for Dogs

Vitamin D

Vitamin D is the only vitamin that can be synthesized by the skin upon exposure to UVB rays in sunlight. However, just because mammals are able to make this vitamin does not mean they don’t need it in their diet. An absence of or weak sunlight(such as during the UK’s winter months) can mean that additional vitamin D is required in an animal’s diet, from sources such as eggs, cod liver oil and saltwater fish. Vitamin D is gaining more and more credit through research for its role in health and immunity, alongside skeletal health.

Roles: Regulates and promotes the absorption of calcium, which is necessary for skeletal health and development. Thought to have roles in immunity and gene transcription.
Deficiency: Signs include skeletal malformations (e.g. rickets, metabolic bone disorder), poor bone health and weak teeth.
Toxicity: Too much can result in vomiting and increased calcium absorption from the intestines, leading to calcium imbalance. Elevated blood calcium may contribute to calcium deposition (calcification) of the soft tissues e.g. heart and lungs, and kidney stones.

Vitamin E

Vitamin E acts as a powerful antioxidant in the body and is also essential for reproduction, immune function, utilization of vitamin K and red blood cell formation. It can be found in seeds, nuts, spinach and other leafy green veg, and is often used as a natural preservative in pet foods. Vitamin E is one of the few fat-soluble vitamins that does not have an upper tolerance limit, however too much in the diet may impact the absorption of other vitamins.

Roles: Protection from free-radical damage. 
Deficiency: Can lead to decreased reproductive performance, impaired immunity and even retinal degeneration.
Toxicity: None known, but high levels can adversely affect the absorption of other vitamins which may then cause deficiency of these nutrients. For example, reduced absorption of vitamin K can prevent normal blood clotting.
Vitapaws products found in: EyeWell for Dogs, JointAid Plus for Dogs

Vitamin K

One of the only vitamins aside from vitamin D that can be generated by the body; vitamin K can be produced by symbiotic bacteria found within the digestive tract (if a healthy gut microbiome exists). Generally, supplementation is not required unless digestive upsets are common, if the dog has had a period on antibiotics, or if there are any other reasons why the gut microbiota might be compromised. In these cases, it may be wise to offer additional dietary sources. Vitamin K can be found naturally in leafy green vegetables, cereals, soybeans, and other veg.  

Roles: Needed for blood clot formation in the body.
Deficiency: Rare due to the body’s ability to synthesise the vitamin internally, however, deficiency can cause increased bruising or prolonged bleeding.
Toxicity: Not known.

Water Soluble Vitamins

The B Vitamins

The B vitamins, collectively known as the Vitamin B Complex, are linked to efficient energy conversion from food, the metabolism, and nerve function. Being water-soluble they are more easily flushed from a dog’s system, so with the exception of niacin (vitamin B3), over-feeding to toxicity is not easily possible, although, before additional supplementation, vets will often recommend testing to establish current levels in the body. 

Vitamin B1 (Thiamine)

Thiamine can be found in whole grains and wheat germ, liver, yeast, most legumes, lean meats and fish. Stability of the vitamin can be affected by heat and oxidation, so some loss will occur when cooking. 

Roles: Essential to the nervous system and muscular function, including the heart, thiamine assists with the conversion of carbohydrates into energy.
Deficiency: Deficiency can cause nerve damage and irregular coordination and seizures. Severe deficiency can even cause brain damage. Thiaminases (enzymes which break down thiamine) are found on the skin of raw fish; a diet high in raw fish can, therefore, cause deficiency. 

Vitamin B2 (Riboflavin)

Riboflavin can be found in liver, yeast, most legumes, cheese, lean meats, fish, nuts and green leafy vegetables. It is more heat stable than Thiamine but can be sensitive to light. 

Roles: Essential to metabolic and enzymatic reactions. Riboflavin also has a role in red blood cell formation and the maintenance of healthy skin and coat. 
Deficiency: Deficiency can cause anaemia and reduced reproductive function, alongside weakness and dry, flaky skin and coat. 

Vitamin B3 (Niacin)

Niacin can be found in liver, yeast, most legumes, lean meats, fish, nuts, seeds and green leafy vegetables.

Roles: Assists with digestive system function, the conversion of food into energy, skin maintenance and nervous function.
Deficiency: Chronic deficiency is sometimes referred to as ‘black tongue’. It can cause loss of appetite, diarrhoea, bad breath and emaciation.
Toxicity: Ingesting too much can cause liver damage, skin complaints and peptic ulcers.

Vitamin B5 (Pantothenic Acid)

As with many other B vitamins, Pantothenic acid can be found in eggs, fish, lean beef, legumes and yeast, as well as potatoes, broccoli and cabbage.

Roles: Assists in enzymatic reactions involved in the metabolism and has a role in hormone synthesis, however, there is no known deficiency from a lack of vitamin B5 in the diet.

Vitamin B6 (Pyridoxine)

Vitamin B6 refers to a group of three compounds: pyridoxol (pyridoxine), pyridoxal and pyridoxamine. Sources of this vitamin include meat, fish, eggs, bananas and whole grains.

Roles: Assists with nervous system function, skin health, red blood cell formation, protein metabolism and the synthesis of antibodies in the immune system. 
Deficiency: Deficiency of pyridoxine can cause dermatitis, alopecia, seizures and anaemia.
Vitapaws products found in: VitaPaws Complete

Vitamin B8 (Biotin)

Biotin is available in foods such as eggs, fish, lean beef, legumes and yeast. There are several forms of the vitamin but only D-biotin is thought to possess the vitamin’s full properties.

Roles: Essential for protein and fat metabolism.
Deficiency: Biotin deficiencies are rare for dogs. Problems associated with deficiency are unknown, however, may be associated with poor skin health. 
Vitapaws products found in: VitaPaws Complete

Vitamin B9 (Folate, Folic Acid)

One of the more well-known B vitamins (due to its advisable supplementation during human pregnancy), Folic Acid or Folate is available in food sources such as yeast, liver, eggs, green leafy veg, melons, carrots and pumpkins, and there are thought to be no ill-effects from over-consumption.

Roles: Essential for protein utilization and synthesis. Vitamin B9 assists with cell production and tissue growth.
Deficiency: Anaemia can be an indication of deficiency, as can issues with new cell formation, including red blood cells. Folic acid supplementation will often be prescribed if a dog is, or has been, on medication that may interfere with folate absorption.

Vitamin B12 (Cobalamin, Cyanocobalamin)

Lastly, vitamin B12, also known as cobalamin or cyanocobalamin, is found in animal-based products such as liver, fish, meat, eggs, poultry and cheese. Many B vitamins are found naturally in meat-based pet foods, however, the recent trend for vegan/vegetarian pet foods means that some dogs can benefit from additional B vitamin supplementation. 

Roles: Necessary for nervous system health (alongside iron and folic acid) and blood formation.
Deficiency: Can cause lack of appetite, anaemia and impaired nervous system function. Deficiency is rare due to most dogs’ common consumption of animal-based products, however, it can be caused by malabsorption in the digestive system. Some breeds are more susceptible to deficiency than others e.g. Border Collies, Beagles and Giant Schnauzers, for which it tends to be hereditary, although it can occur at any age.
Vitapaws products found in: VitaPaws Complete

Vitamin C

Also referred to as ascorbic acid, vitamin C is a water-soluble vitamin that is produced naturally in the dog’s liver and is, therefore, is not strictly required in the canine diet. Many pet food companies take advantage of this and do not include added vitamin C in their dog food, however, additional dietary sources can be beneficial to a dog’s immunity, skin health and collagen formation in joints. Foods containing vitamin C include berries, potatoes (skins), green leafy vegetables and tomatoes. Although always check which foods are suitable to be fed to dogs as part of a balanced diet.

Roles: Protection from free-radical damage, joint health and immune support. Can assist in the absorption of iron.
Deficiency: Can lead to impaired immune function and slower skin healing.
Toxicity: High amounts are thought to have a laxative effect and can cause diarrhoea. As a water-soluble vitamin, vitamin C is easily excreted by the body. Too much vitamin C in the diet may impair vitamin B12 absorption. 
Vitapaws products found in: EyeWell for Dogs, JointAid Plus for Dogs

For further reading, advice on which foods to feed and guidelines on the amount of each nutrient that’s recommended daily for a dog, visit the FEDIAF* website and download the nutritional guidelines for cats and dogs. 
*the trade body representing the European pet food industry

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References
DSM (2018) Riboflavin [online]. Accessed at: https://www.dsm.com/markets/anh/en_US/Compendium/companion_animals/riboflavin.html
FEDIAF (2018)  FEDIAF Nutritional Guidelines for Complete and Complementary Pet Food for Cats and Dogs [online]. Available at: http://www.fediaf.org/self-regulation/nutrition.html (accessed 03.01.2019)
Frigg, M., Schulze, J., & Völker, L. (1989). Clinical study on the effect of biotin on skin conditions in dogs. Schweizer Archiv fur Tierheilkunde, 131(10), 621-625.
Kritikos, G., Parr, J., & Verbrugghe, A. (2017). The Role of Thiamine and Effects of Deficiency in Dogs and Cats. Veterinary sciences, 4(4), 59.
National Research Council. 2006. Nutrient Requirements of Dogs and Cats. Washington, DC: The National Academies Press. https://doi.org/10.17226/10668.
 

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