Do Dogs Need Vitamins?

Most dogs don't need vitamins. A healthy dog eating a complete and balanced dog food already gets the vitamins and minerals it needs. The ASPCA, WSAVA and AAFCO all say a supplement is generally unnecessary on that diet.

That includes puppies on a complete puppy food, and Merck cautions against extra calcium and vitamin D for growing puppies. Below: how to check your dog's food, when a vet might suggest a supplement, and how to choose one.

What do vitamins actually do for a dog?

Vitamins do their work in tiny amounts. The ASPCA puts it simply: small amounts are necessary for normal metabolic function.

Dogs are more flexible than cats in a few ways. The Merck Veterinary Manual notes that dogs can readily use both plant and animal sources of vitamin A, and can make niacin, a B vitamin, from the amino acid tryptophan. Cats can do neither.

They also make their own vitamin C. According to Merck, dogs and cats produce it from glucose in the liver.

Here's a surprising one. Skin makes vitamin D from a compound called 7-dehydrocholesterol when exposed to UV light. Merck notes that dogs and cats have very limited amounts of it.

All of this is already built into a dog food that is complete and balanced.

What does "complete and balanced" mean?

It's the phrase to look for. AAFCO defines "complete" as containing all the nutrients required, and "balanced" as having them in the correct ratios.

The FDA explains that a food with this claim is intended to be fed as a pet's sole diet. To make it, the food must either meet one of AAFCO's dog food nutrient profiles or pass a feeding trial run under AAFCO procedures.

The claim sits in the nutritional adequacy statement, usually in small print on the bag or can. AAFCO calls this statement the key to meeting a pet's nutritional needs.

It also names a life stage. AAFCO's life stages are growth (puppies), adult maintenance, pregnancy and nursing, and all life stages.

A product marked "for intermittent or supplemental feeding only" is a different thing. AAFCO uses that wording for treats and supplements, which are meant to be fed in addition to a complete diet.

Do puppies need vitamins?

Puppies need more nutrients than adults, and a good puppy food is where they come from. Merck's puppy care guide says puppies need food that provides enough calories, fat, protein, vitamins and minerals for growth, and suggests looking for the AAFCO statement.

Adding to it is where the risk sits. Merck's guidance on feeding is direct: supplementing calcium, phosphorus or vitamin D beyond what a complete growth diet provides is rarely necessary and may be inadvisable.

Here's why. Merck explains that young puppies, from weaning to about 6 months, may not be able to limit how much calcium they absorb when there is too much in the diet.

Large- and giant-breed puppies are the most sensitive. Merck notes that excess calcium is more of a concern for them from weaning to one year.

Its owner guide adds that giant-breed dogs fed excess calcium are more likely to develop disorders of bone and cartilage growth.

So a puppy on a complete growth food needs no calcium or vitamin supplement unless your vet prescribes one. Our guide to what to feed a puppy covers choosing that food and how much to give.

Can a dog get too many vitamins?

Yes. AAFCO warns that supplementing a complete and balanced diet risks exceeding the upper limits of certain nutrients.

Not every vitamin carries the same risk. Merck explains that water-soluble vitamins have much less potential for harm than fat-soluble ones, because excess is not readily stored in the body.

Vitamin A

The ASPCA lists what too much vitamin A can do to a dog: bone and joint pain, brittle bones and dry skin.

Merck adds that feeding only liver can cause vitamin A excess in dogs and cats.

Vitamin D

Vitamin D is essential. The FDA describes it as the nutrient that helps dogs regulate the balance and retention of calcium and phosphorus.

It also has little room for error. AAFCO notes a fairly small difference between what's needed and what's toxic, particularly for dogs. The FDA explains that the body stores excess in fat and the liver instead of passing it in urine.

The FDA warns that too much can seriously harm the kidneys and can be fatal. Excess from food builds slowly, while a dog that gets into a vitamin D supplement can show signs within hours or days.

When might a vet recommend a supplement?

The reasons are specific. The ASPCA's position is that a vitamin supplement is unnecessary on a complete and balanced diet unless a vet diagnoses a specific deficiency.

Homemade food is the other common case. Merck notes that studies show many homemade dog diets lack minerals and miss the right calcium-to-phosphorus ratio. It recommends a quality commercial food, or a recipe designed by a credentialed veterinary nutritionist.

WSAVA names one possible exception on commercial food: essential fatty acids. Longer-coated breeds may need slightly higher intakes for skin and coat quality, it says.

For those dogs, WSAVA suggests a fatty acid supplement or a change of food may help. Our guide to omega-3 for dogs looks at the evidence.

In each case the vet chooses the product and the amount. AAFCO advises owners to use the vet-prescribed dosage and follow the directions.

If you do use one, how do you choose?

Talk to your vet first. AAFCO recommends it before any supplement, and WSAVA adds that supplements need careful evaluation for safety and effectiveness.

• Choose a product made for dogs, and keep your own vitamins out of reach. Merck notes that pets eating human vitamins is common, and some contain ingredients toxic to animals, such as xylitol.
• Read the whole label. If a product adds calcium, vitamin A or vitamin D, ask your vet whether your dog's food already supplies enough.
• Avoid stacking mineral products. Merck warns that indiscriminate mineral supplementation can cause a mineral imbalance.
• Give the amount on the label or the amount your vet sets, and no more.

If you and your vet decide a daily extra suits your adult dog, it sits alongside a complete diet and never replaces it.

Choolip's Total Balance is one example: a lickable stick made with tuna, cod, salmon and lobster, fortified with vitamins A, B2, B3 and E, iron, zinc and a postbiotic.

It's a food supplement, not a complete diet, and a dog on complete food doesn't need it. Show your vet the label along with anything else your dog takes.

How are pet supplements regulated?

Differently from human ones. The FDA states that products sold as dietary supplements for animals don't fall under DSHEA, the law that covers human supplements. It regulates them as either food or animal drugs, depending on their makeup and intended use.

Animal food doesn't need FDA review before it goes on sale.

A product that claims to treat or prevent disease is regulated as a drug and needs FDA approval, so a supplement making that kind of claim is a reason to ask your vet before buying.

What if my dog gets into vitamins?

Call your vet straight away. Merck's toxicology chapter notes that signs of vitamin D poisoning can appear within 12 to 48 hours of a large exposure.

Call your vet promptly if your dog:

• has eaten a human vitamin or supplement, or more of a pet one than the label allows
• has eaten a rat or mouse bait, since the FDA notes some contain vitamin D (cholecalciferol)
• is throwing up, off their food, drinking or peeing more than usual, drooling a lot or losing weight

Questions new puppy parents ask

Do puppies need vitamins?

Not on a complete and balanced puppy food. Merck says extra calcium, phosphorus or vitamin D on a complete growth diet is rarely necessary and may be inadvisable.

Are multivitamins for dogs worth it?

For a healthy dog on complete food, WSAVA says there is no need to add vitamin or mineral supplements. If you're considering one, ask your vet.

Can I give my dog human vitamins?

No. Merck notes that some human vitamins contain ingredients toxic to animals, including xylitol, and the FDA warns about dogs getting into household vitamin D supplements.

Do cats and dogs need the same vitamins?

No. Cats need vitamin A in ready-made form and all their niacin from food, while dogs can use plant sources of vitamin A and make niacin from tryptophan. Our guide to cat vitamins covers the feline side.

Sources

• ASPCA: Dog Nutrition Tips
• WSAVA Global Nutrition Committee: Frequently Asked Questions and Myths
• Merck Veterinary Manual: Nutritional Requirements of Small Animals
• Merck Veterinary Manual: Feeding Practices in Small Animals
• Merck Veterinary Manual: Disorders Associated with Calcium, Phosphorus, and Vitamin D in Dogs
• Merck Veterinary Manual: Puppy Care
• Merck Veterinary Manual: Toxicoses in Animals From Human Multivitamins and Supplements
• AAFCO: Supplements
• AAFCO: Selecting the Right Pet Food
• FDA Center for Veterinary Medicine: “Complete and Balanced” Pet Food
• FDA Center for Veterinary Medicine: FDA’s Regulation of Pet Food
• FDA Center for Veterinary Medicine: Vitamin D Toxicity in Dogs

This article is for general information and is not veterinary advice. Talk to your vet about your own dog — they know the animal in front of them.