Vitamins for Dogs: Benefits and Side EffectsVitamins are regular among people, but do vitamins for dogs work the same way?

Vitamins are organic compounds and vital nutrients that your dog requires in small amounts.

These compounds are called a vitamin when your dog cannot synthesize the substance in sufficient quantities and must therefore be obtained through the diet.

This means the term “vitamin” depends on the circumstances and the particular organism, in this case, your individual dog.

Giving vitamin supplementation is important for the treatment of certain health problems.

However, there is little evidence of nutritional benefit when used by otherwise healthy dogs.


Types of vitamins for dogs

There are thirteen vitamins total that are recognized. Each is composed of one or more compounds called vitamers.

Commonly, the vitamer name is used instead of the vitamin name. The table below lists the 13 vitamins and their vitamers.

Vitamin A – Retinol/Retinal/four carotenoids including beta carotene
Vitamin B1 – Thiamine
Vitamin B2 – Riboflavin
Vitamin B3 – Niacin/Niacinamide
Vitamin B5 – Pantothenic acid
Vitamin B6 – Pyridoxine/Pyridoxamine/Pyridoxal
Vitamin B7 – Biotin
Vitamin B9 – Folic acid/Folinic acid
Vitamin B12 – Cyanocobalamin/Hydroxycobalamin/Methylcobalamin
Vitamin C – Ascorbic acid
Vitamin D – Cholecalciferol (D3)/Ergocalciferol (D2)
Vitamin E – Tocopherols/Tocotrienols
Vitamin K – Phylloquinone/Menaquinones

Benefits of vitamins for dogs

Vitamins are classified by their biological and chemical activity, not their structure. They have a wide range of functions.

Some act like hormones in the regulation of metabolism of minerals (e.g. vitamin D) or regulate the growth of cells and tissues. Others are anti-oxidants (e.g. vitamins C and E).

The largest number of vitamins, the B-complex, function as the building blocks of enzymes – the catalysts in metabolism; biotin is part of enzymes involved in making fatty acids.

Fat soluble vitamins

Vitamins for Dogs and Canines - Benefits and Side Effects

Vitamin A

Vitamin A is found in several forms such as retinoic acid, retinol, retinaldehyde and in the liver storage form, retinyl palmitate.

Vitamin A has many roles and helps your dog with his vision (particularly night vision), skin and coat condition, tissue growth and health, tooth and skeletal development and reproduction processes.

If you raise puppies, the role of vitamin A in growth is of particular importance.

Lack of vitamin A in puppies directly relates to retarded growth rates, weakness in the muscle, vision problems, a poor coat condition, skeletal and nervous disorders such as hydrocephalus and cleft palate.

Female dogs will not ovulate properly and males can become sterile if they are deficient in vitamin A.

Vitamin D

Vitamin D plays a major role in regulating the calcium and phosphorous levels within the bloodstream.

Vitamin D stimulates the kidneys to conserve calcium thereby helping the body to retain the mineral, therefore, vitamin D is extremely important in bone formation and nerve and muscle control.

Vitamin E

Vitamin E plays a major role in the formation of membranes surrounding cells, the respiration of cells, fat metabolism and as an anti-oxidant.

Vitamin K

Vitamin K for dogs is essential for normal blood functions such as clotting.

It is not required in high concentrations in supplements because the bacteria in your dog’s intestine can manufacture vitamin K.

Water soluble vitamins

Vitamin C

Vitamin C for dogs acts as an anti-oxidant and is an important nutrient in the synthesis of collagen and cartilage.

Dogs can manufacture their own vitamin C and do not require it in their diet like humans do, so the value of supplementing vitamin C remains unclear.

Vitamin C has been thought to prevent hip dysplasia in dogs. It seems highly unlikely that its use will prevent a dog developing this genetically carried trait, however, it may help alleviate the pain arising from the condition.

Vitamin C is also thought to prevent urinary tract infections and bladder stones.

Furthermore, vitamin C plays many important functions in bone formation, both in growth and mineralization. Deficiencies of vitamin C result in the syndrome known as scurvy which in dogs, causes weak bones and swollen joints.

Vitamin B-complex

Vitamin B-complex consists of a multitude of B vitamins.

Vitamins B1, B2, B3, and biotin participate in different aspects of the production of energy in cells.

Vitamin B6 is essential for the metabolism of amino acids. Vitamin B12 and folic acid ire involved in the division of cells.

B vitamins are important in maintaining a suitable environment for neural regeneration and growth.

Deficiency of B vitamins can result in a reduction of nerve reflexes and nervous control, retarded growth, a loss of appetite, loose stools, poor coat, abnormalities of the eyes, and potentially heart failure.

B-complex (in particular B2 and B6) is also essential for the prevention of bladder stone formation in dogs.

Side effects of vitamins for dogs

Solubility and toxicity

The primary vitamins are often classified according to their solubility in fat or water, which influences their potential for causing problems if your dog is over-supplemented.

The fat soluble vitamins are A, D, E, and K.  The vitamins C and B-complex are designated as water soluble. The fat soluble vitamins are stored in lipocytes (specialised fat storage cells). Because the body stores fat soluble vitamins, there is a greater risk of problems from these if your dog is over-supplemented.

The water soluble vitamins are not stored within the body, except in very small amounts, and if over-supplemented, your dog will easily eliminate this from his body in urine and thereby give a minimal risk of toxic effects.

Side effects due to overdose

The table below lists the potential consequences of over-supplementation of each of the 13 recognised vitamins.

It lists the diseases experienced by humans as the information for dogs is considerably less detailed. Please consult your veterinarian for further information.

Vitamin A – Hypervitaminosis A (Vision changes, liver damage, dehydration, vomiting, decreased appetite, constipation, fatigue, skin and hair changes, higher sensitivity to sunlight, oily skin and hair (seborrhea), irritability)
Vitamin B1 – Muscle relaxation with large doses, drowsiness
Vitamin B2
Vitamin B3 – Liver damage and other problems
Vitamin B5 – Diarrhea, nausea, heartburn
Vitamin B6 – Nerve damage
Vitamin B7
Vitamin B9 – May conceal vitamin B12 deficiency symptoms
Vitamin B12 – Acne-like rash – rare
Vitamin C – Loose stools, kidney stones, an increase in uric-acid excretion, kidney stones, scurvy, reduced absorption of copper and vitamin B12, increased oxygen demand, acid erosion of the teeth
Vitamin D – Hypervitaminosis D (dehydration, vomiting, a decrease in appetite, hard feces and constipation, tiredness and weakness of the muscles)
Vitamin E – Potential for increased congestive heart failure
Vitamin K – Increases blood coagulation in dogs taking warfarin


  1. I don’t know where you’re getting the facts about Vitamin E increasing risk for congestive heart failure? Everything I’ve read states to GIVE it to dogs in heart failure. In fact, people report it actually stopping CHF and getting dogs out of it. So give me some real studies to prove what you’re saying please?!

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