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Person feeding a dog vitamins

The essentials

  • Vitamins are essential for life — Dogs, humans, and other living organisms get most of these organic compounds from food.
  • Dog supplements can make up for an imbalanced diet — When the vitamins in your dog’s diet aren’t enough, they can take supplements to target and strengthen different parts of the body.
  • They can be dangerous in large quantities — Consult your vet to determine the best doses of different vitamins for your dog.

While most commercially prepared dog foods are formulated to make up a complete and balanced diet, many dogs can benefit from incorporating vitamin and mineral supplements into their daily regimen — especially as their nutritional needs change due to age, breed, or underlying health issues.

Different vitamins support different organs and systems throughout the body. Multivitamins are particularly popular among dog owners because they contain all the vitamins essential to a dog’s health, including vitamin A, B vitamins, vitamin C, vitamin D, vitamin E, vitamin K, and choline.

We’ll dive into the benefits of each one of these compounds below.

Before you give your dog vitamin supplements

Always consult a veterinarian before starting your dog on any new vitamin or supplement. They’ll be able to run the appropriate tests and determine the best supplement (if any) for your dog’s particular condition or deficiency.

While vitamins are essential to maintaining a dog’s overall health, there is a risk of overdose with certain compounds. Some supplements are formulated with herbs that can trigger adverse reactions when consumed in combination with certain medications. Alternatively, chronic toxicity can occur as the result of over-supplementation over time.

Symptoms of vitamin poisoning vary depending on the vitamin, but some common signs include:

  • Fever
  • Fatigue
  • Loss of appetite
  • Nausea
  • Vomiting
  • Diarrhea
  • Rapid heartbeat
  • Abdominal pain and swelling
  • Tremors and shakes
  • Seizures

1. Vitamin A

Most famously found in carrots, Vitamin A supports strong bones, a healthy immune system, as well as growth and fetal development in the earliest stages of a dog’s life. Vitamin A also supports clear vision, and it can be found in many popular eye care supplements for dogs.

Vitamin A is considered a fat-soluble vitamin because it’s absorbed alongside the fats dogs eat, and can be stored in the liver and other fat tissues until their body needs it. This makes it harder for dogs to be deficient in these vitamins if they’re already a part of their diet. On the other hand, it also makes it easier for fat-soluble vitamins to build up to toxic levels.

What happens if your dog gets too much vitamin A

Symptoms of Vitamin A poisoning can appear suddenly or be delayed in their onset. Mild cases might simply result in dehydration and joint pain, but dogs may also experience drowsiness, irritability, vomiting, and peeling of the skin if they ingest a particularly large dose.

Long-term vitamin A over-supplementation can slowly lead to dry or damaged skin; a patchy, lackluster coat; weight loss; excessive bone development; and limited mobility due to joint pain. In the case of pregnant dogs, too much vitamin A can lead to the development of fetal abnormalities like a cleft palate.

2. B Vitamins

Each member of the B vitamin group — also known as the vitamin B complex — plays a unique role in your dog’s health. Key compounds in this group include thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), vitamin B6, biotin (B7), folic acid (B9), and vitamin B12.

Fish, chicken, lamb, eggs, wheat, and rice are dog-safe sources of B vitamins. Many of the compounds in this group are crucial for converting food into glucose for energy. Vitamin B6 is especially important as it supports the nervous system, and immune responses like gene activation, brain function, red blood cell generation, and hormone regulation.

Biotin has been shown to nourish a dog’s skin and coat by supporting the production of fatty acids and preventing excess water loss.

Riboflavin, niacin, and B12 support healthy enzyme function, which in turn regulates digestion and appetite. These vitamins can be supplemented with probiotics and digestive enzymes, both of which help the body absorb nutrients from food better.

🚨If your dog suffers from dandruff or dry skin, they may be deficient in vitamin B.

What happens if your dog gets too much vitamin B

B vitamins are water-soluble, which means your dog will pee out whatever their body can’t use. This makes the risk of vitamin B overdose incredibly low, but certain compounds like niacin can still cause skin sores and liver damage if ingested in high enough doses. Some studies have also shown high doses of vitamin B6 can lower red blood cell counts and trigger a loss of muscle control.

3. Vitamin C

Unlike other vitamins on this list, vitamin C is naturally synthesized inside a dog’s liver from raw ingredients in their food. Vitamin C is an antioxidant that removes free radicals from the body to reduce inflammation and slow down the process of cognitive aging. It’s also been shown to promote healthy teeth, bones, and iron absorption.

While most healthy dogs don’t need vitamin C supplementation, an extra boost can benefit dogs with conditions like liver disease, distemper, and hip dysplasia. Vitamin C supplements can also be good for dogs with high metabolisms, who burn through their body’s natural reserves much faster than normal.

What happens if your dog gets too much vitamin C

Like vitamin B, vitamin C is a water-soluble compound that is excreted through a dog’s urine when consumed in excess. However, too much vitamin C can result in the creation of calcium oxalate bladder stones, especially in male dogs, whose elongated urethras put them at higher risk of this side effect. Symptoms of bladder stones include urinary blockage and/or blood in the urine.

4. Vitamin D

Famous for its association with sunshine, vitamin D facilitates healthy bone growth, muscle development, and joint function by balancing minerals like phosphorus and calcium inside a dog’s body.

Vitamin D comes in two primary forms: vitamin D2, which is found in plant-based sources like fungi and yeast, and vitamin D3, which is found in animal products like beef, fish, liver, and eggs. D3 produces concentrations in the bloodstream nearly twice as high as those of vitamin D2.

What happens if your dog gets too much vitamin D

Vitamin D poisoning is a serious condition in dogs that can be life-threatening if left untreated. This type of poisoning most commonly occurs when dogs accidentally ingest rodenticides (rat and mouse poisons) or topical psoriasis ointments, which they can directly lick off someone’s skin.

Symptoms of vitamin D poisoning occur 12 to 36 hours after ingestion, and are usually more severe the more a dog consumes. Smaller doses may result in depression, decreased appetite, increased drinking and urination, abdominal pain, vomiting, and diarrhea. More severe cases are marked by difficulty breathing, an increased respiratory rate, slow or abnormal heart rhythms, intestinal bleeding, and kidney failure.

5. Vitamin E

Vitamin E is a powerful antioxidant that’s essential for proper puppy development, cell function, and fat metabolism. Added benefits include improved heart, brain, and immune function, as well as improved skin and coat health. Vitamin E’s effectiveness against free radicals in the body makes it especially beneficial to sick and older dogs.

Vitamin E deficiency can lead to reproductive problems, poor vision, neurological symptoms, and muscle degeneration. Most pups get sufficient vitamin E from their kibble since the Association of American Feed Control Officials (AAFCO) standards require all commercially prepared dog foods to contain at least the minimum amount of vitamin E necessary for a dog’s health.

Some multivitamins and fish oil supplements like salmon oil can be used to combat vitamin E deficiency. Alternatively, dog-safe foods like eggs, salmon, spinach, and sunflower oil are great natural sources of vitamin E.

What happens if your dog gets too much vitamin E

Though vitamin E is a fat-soluble compound, overdose is still relatively rare among dogs. Cases of acute overdose may result in gastrointestinal upset accompanied by vomiting and diarrhea. In contrast, chronic overdose can lead to decreased absorption of the other fat-soluble vitamins including A, D, and K.

6. Vitamin K

Vitamin K is essential for maintaining a dog’s blood-clotting function, a key mechanism when it comes to healing injuries and preventing excess bleeding. Studies show that vitamin K may also help prevent heart disease by reducing harmful calcium buildup in the arteries.

Dogs usually produce sufficient vitamin K with the help of their internal gut bacteria, so most won’t require dietary supplementation. Leafy greens like broccoli, brussels sprouts, and cabbage are natural sources of plant-based vitamin K1, while ground beef, chicken, cheeses, and eggs contain healthy levels of vitamin K2.

Some rodenticides can inhibit a dog’s ability to use vitamin K properly, which can result in internal hemorrhaging and death if left untreated.

What happens if your dog gets too much vitamin K

Even in high doses, both naturally-occurring forms of vitamin K are considered completely safe for dogs when ingested orally. Some dogs may experience allergic reactions after being injected with K1 or K2, with particularly severe cases resulting in cardiac arrest.

A synthetic form of vitamin K known as vitamin K3 or menadione can result in hemolytic anemia and liver cell damage, but it’s unlikely your dog will ever come into contact with it since it’s banned in US over-the-counter sales.

🚨Read through your dog food ingredients to make sure your dog isn’t ingesting vitamin K3. 

7. Choline

Choline is an essential building block for cell membranes, the protective sheaths around nerves, and the neurotransmitter acetylcholine, which regulates vital functions like heart rate, muscle contractions, and blood vessel dilation. It also assists in hormone production and fat and cholesterol metabolism inside a dog’s body.

Vets use choline’s foundational properties to reduce seizure frequency in cats and dogs suffering from epilepsy and other cognitive disorders like cognitive dysfunction syndrome (CDS). Choline has also proved effective in reducing the insulin requirements of dogs with diabetes.

What happens if your dog gets too much choline

VCA Animal Hospitals advises owners to exercise caution when feeding their pets choline supplements since studies and information regarding potential side effects are still limited. Higher doses may result in mild symptoms including agitation and hyperactivity, while more serious side effects include low blood pressure, extreme drowsiness, and vomiting.

When does your dog need a vitamin?

Complete and balanced commercial dog food should always be a dog’s main source of necessary vitamins. Today, commercial pet food manufacturers are required by law to formulate their products with all the vitamins, nutrients, and minerals dogs need to stay healthy.

Some commercial dog foods contain different levels of key vitamins to cater to specific types of dogs. Dogs of different ages may require food specially formulated for puppies, adult dogs, or senior dogs to adequately fulfill their nutritional needs. Similarly, larger dogs require large-breed puppy foods specifically formulated to prevent the onset of conditions like hip dysplasia.

As long as your dog is eating the right dog food, they shouldn’t need any additional vitamins or supplements. Your dog may need vitamins if you’re feeding them a homemade diet, but it’s important to consult a vet on the correct type and dosage before starting them on anything. We might be able to just take a supplement with breakfast or dinner and go on with our day, but it’s not so simple for our furry best friends.

How to choose the right vitamins for your dog

Think your dog might benefit from vitamins and supplements? Follow these steps to make sure you’re giving them the right product for their needs:

  • See a vet. Always consult a vet before introducing a new vitamin to your dog. They’ll be able to tell you exactly which vitamins your dog needs for their particular deficiency or medical condition.
  • Stick to doggie vitamins. Multivitamins and supplements intended for human consumption often contain differing levels of key vitamins, and may also be formulated with additives that are toxic to dogs. Avoid giving human supplements to your dog and stick to brands specifically intended for canine consumption.
  • Read the label. Always check the dosage and ingredients listed on the label before buying a vitamin for your dog.

Vitamin supplements may be a waste of money and could be detrimental, in some situations. Go with a balanced diet and ask your vet if omega 3 and glucosamine/chondroitin supplements are necessary for your vet. Dogs with confirmed deficiencies (like zinc-responsive dermatoses in Nordic breeds) should receive vitamin supplements.

Dr. Erica Irish

Vitamins make life possible. This is just as true for us as it is for our pets — but that doesn’t necessarily mean our dogs need supplements to thrive. In most cases, you can keep your pooch healthy just by feeding them quality dog food tailored to their age and breed.

If you think your dog could benefit from an extra boost beyond their daily nutrition, talk to a vet. You may also find it helpful to speak to a licensed nutritionist about your dog’s dietary needs. Don’t be afraid to ask questions, and remember that you’re doing this to give your buddy the best quality of life possible.

Frequently asked questions

What vitamin is best for dogs?

No one vitamin is “better” for dogs than another, since they all offer unique health benefits. Compounds like vitamin A, vitamin B complex, vitamin C, vitamin D, vitamin E, vitamin K, and choline are all considered essential for maintaining a properly functioning body.

What vitamins do dogs need in dog food?

Vitamin A, vitamin B complex, vitamin C, vitamin D, vitamin E, vitamin K, and choline are all essential to a dog’s health. Minerals like calcium and phosphorus are considered equally important, as are fundamental nutrients like proteins, carbohydrates, and fats like linoleic acid, omega 3, and omega 6.

Can you give a dog human vitamins?

While some vitamins and supplements intended for humans may be harmless to your dog, it’s best to err on the side of caution and only feed them vitamins intended specifically for pets.

Can I give my dog vitamins everyday?

Daily vitamins can be extremely beneficial to some dogs, but you should never start your dog on any supplement without consulting a vet first. They’ll be able to determine the best regimen for your dog based on factors like their age, size, diet, and overall health.

What can I supplement my dog’s food with?

If you feel like giving your dog a tasty treat every once in a while, you might try supplementing their diet with whole foods like scrambled eggs, cooked lean meats like beef or chicken, or dog-friendly fruits and veggies like blueberries, carrots, sweet potato, and leafy greens. You can also give them pet-formulated dietary supplements if they’re deficient in a particular kind of vitamin.