Which Vitamins Do Dogs Need?
There are quite a few vitamins that dogs require from their food. They can be separated into two categories: fat-soluble and water-soluble.
Fat-soluble vitamins require bile salts and fat in order to be absorbed in a dog’s gut. There are four fat-soluble vitamins: A, D, E, and K. Due to the way fat-soluble vitamins are stored and used by the body, they are at the highest risk for deficiency and/or toxicity.
Vitamin A, also known as retinol, is essential for normal vision, growth, reproduction, immune function, and healthy skin.
AAFCO recommends 5,000 IU/kg DM for dogs for all life stages.
Vitamin A deficiency can cause night blindness and skin issues. Toxicity can occur with over-supplementation and can cause bleeding and abnormal bone growth and formation.
Natural sources with the highest amounts of vitamin A include:
Vitamin A is not stable on its own, and in many cases, needs a protective coating to ensure absorption. Deficiencies can cause decreased eating or anorexia, stunted growth, dull hair coat, and weakness. Toxicities can cause stunted growth, anorexia, and bone fractures.
Vitamin D, also known as cholecalciferol (D3) and ergocalciferol (D2), is essential for dogs since they are unable to produce it naturally in the body. Vitamin D helps the intestine with absorption and helps to retain calcium and phosphorus in the bone.
AAFCO recommends 500 IU/kg DM for dogs for all life stages.
Marine fish and fish oils are the richest natural sources, but they can pose a risk for overdose. Other sources include freshwater fish, eggs, beef, liver, and most dairy. The most common synthetic sources are vitamin D3 and vitamin D2 supplements.
Deficiencies can cause rickets, enlarged joints, osteoporosis, and other bone issues. Toxicities can include hypercalcemia, decreased eating or anorexia, and lameness.
Vitamin E, also known as alpha-tocopherol, functions as an antioxidant in the body.
Deficiency can cause decreased eating or anorexia, skin and immune issues, and neurologic concerns in dogs. It is the least toxic fat-soluble vitamin. Toxicity is rare but can interfere with clotting times and mineralization of the bones.
AAFCO recommends 50 IU/kg DM for dogs.
Only plants synthesize vitamin E. Vegetable oils, seeds, and cereal grains have the richest sources of vitamin E for dogs.
Vitamin K, also known as menadione, is involved in blood clotting and bone development.
There is no recommended allowance for vitamin K in dogs, but AAFCO recommends 1.64 mg/kg for puppies and adults.
Deficiencies of vitamin K can cause prolonged clotting times and hemorrhage. They can occur due to underlying medical conditions that impair absorption of vitamin K in the gut (such as inflammatory bowel disease). Certain forms of vitamin K can cause anemia and jaundice.
If vitamin K supplementation is recommended by your veterinarian, ask which sources would be best for your pet. Foods such as alfalfa meal, oilseed meals, liver, and fish meals are rich sources of vitamin K.