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Vitamin C for Dogs – Benefits, Dosage, Risks & Best Supplements

Written by Jay
BsC (Hons) Animal Behaviour & Welfare graduate with a passion for advocating for misunderstood animals.
Published on
Wednesday 24 June 2020
Last updated on
Tuesday 9 May 2023
vitamin c for dogs
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Many owners are curious to find out if vitamin C for dogs offers any benefits. While dog vitamin C does offer some advantages in some cases, in others it appears to have little effect. This is because dogs, unlike humans, synthesize their own vitamin C.

In addition, vitamin C deficiency in dogs is not widely studied due to its rarity. As with any health supplement, it’s important to evaluate the advantages and disadvantages first. This allows owners to make informed decisions.

Benefits of Vitamin C for Dogs

Vitamin C is a powerful antioxidant. It helps to reduce inflammation, supports a healthy immune system and aids in collagen synthesis. Dogs produce vitamin C by themselves in the liver, but in some rare cases, supplementation is provided to offer health benefits. It’s also important to note that vitamin C supplementation can actually make some conditions worse. For example, canine hypertrophic osteodystrophy (HOD) is further aggravated by vitamin C supplements.

Fights Inflammation

In simple terms, inflammation is the body’s response to a physical threat. Whether the threat is a splinter, sunburn, or a broken bone, inflammation acts to remove the problem. Inflammation is the body’s natural healing process. The process is uncomfortable and brings out several symptoms at the affected site: pain, redness, immobility, heat, and swelling. These inflammation symptoms only apply to the skin.

When inflammation occurs deeper inside the body, such as in an organ, only some or none of these signs are noticeable. This is because some organs have no sensory nerve endings. Higher intakes of vitamin C are inversely associated with reduced levels of inflammation markers. This means that the higher the amount of vitamin C, the lower the inflammation in the body. This is because vitamin C is an antioxidant that decreases oxidative damage in the body.

This does not mean that vitamin C supplements are always the best course of treatment for inflammation. For example, osteoarthritis and rheumatoid arthritis both present with inflammation as a symptom, although it’s less common in osteoarthritis. While vitamin C is shown to be beneficial in rheumatoid arthritis, dogs with osteoarthritis suffer more bone spurs as a result of supplementation. If your dog suffers from inflammatory symptoms, it’s best to seek out a diagnosis before attempting to treat a potentially dangerous underlying condition.


Macrophage cells produce free radicals whilst fighting germs in the body. Free radicals cause damage to healthy cells which produces an inflammatory response. In healthy individuals, this inflammation resolves once the immune system eliminates the infection. However, the resulting oxidative stress can also call for another inflammatory response. This causes more free radicals to develop, creating an endless cycle.

This is where vitamin C comes in. This vitamin is a powerful antioxidant. It’s also able to donate a hydrogen atom to a free radical to form a more stable ascorbyl-free radical. Vitamin C scavenges other harmful oxygen-derived species like hydrogen peroxide and hydroxyl radicals. By reducing oxidative damage in this way, vitamin C also lowers the risk of developing certain chronic diseases. This does not mean that it renders your pet immune to chronic diseases, so keep attending your annual vet checks for peace of mind.

antioxidants in vitamin c
Vitamin C is a powerful antioxidant!

Boosting the Immune System

Vitamin C contributes to the immune system by supporting cellular functions. This vitamin accumulates within phagocytic cells like neutrophils. It enhances phagocytosis and chemotaxis. As well as this, vitamin C helps to generate reactive oxygen species and apoptosis. Spent neutrophils are also removed with the help of vitamin C. This reduces necrosis and damage to tissues. Vitamin C enhances the differentiation of B-cell and T-cell lymphocytes. During stress or anxiety, glucocorticoids suppress the body’s immune response. To counter this, vitamin C reduces glucocorticoid synthesis which helps the dog to maintain some immunocompetence.

Production Of Collagen

Collagen is a hard, insoluble protein that makes up one-third of the body’s protein. Most collagens form fibrils. These fibrils are supporting structures that anchor cells to one another. This gives skin elasticity. The body consists of at least 16 types of collagen, but the vast majority belong to types 1, 2 and 3. Type 1 collagen is the most abundant type and is a key structural component of several different tissues.

Vitamin C regulates the synthesis of collagen, more specifically, type 1 collagen. It does this through the hydroxylation of collagen molecules. Hydroxylation is needed to maintain extracellular stability and to support the epidermis. Furthermore, vitamin C stabilizes collagen mRNA, which allows an increase in collagen protein synthesis to repair damaged skin. Prolonged vitamin C deficiency in dogs causes slower wound healing. However, if your dog has a wound that’s slow to heal, it’s important to seek veterinary aid before providing any supplements to try to heal it. Vitamin C alone is not enough to effectively fight infections.

Vitamin C Dosage in Dogs

There is no established dose recommendation for dogs. Researches propose doses of 30mg to 100mg, but none are concrete. Some researchers are adamant that vitamin C supplements offer little benefit to healthy dogs, while other sources suggest that it can significantly help to support your dog’s health. Whether you use vitamin C is ultimately your decision as an owner, so be sure to research the benefits and negatives before giving supplements to your dog.

There are two forms of vitamin C that are most recommended: calcium ascorbate and sodium ascorbate. These forms are the most gentle forms of vitamin C. They also produce fewer side effects like heartburn and diarrhea.

Dosage For Dogs

Proponents of vitamin C supplementation suggest that the following doses are appropriate for dogs, although doses vary between sources:

  • Puppies: 100mg
  • Small dogs: 250mg
  • Medium dogs: 500mg
  • Large dogs: 750mg

If you plan to use vitamin C to help to treat a specific illness in your dog, it’s crucial that you ask your veterinarian for advice. You will need to know how often and how much of the supplement to give your dog, and this will change depending on what your pet’s condition is.

Some vitamin supplements come with a scoop. This allows for easy measurement of the dose for your pet. Other vitamin supplements for dogs require you to measure out the dose yourself. Do not be tempted to exceed the dose. While it may be tempting to offer your dog the highest amount of vitamins possible, too many vitamins can actually do more harm than good.

Vitamin C Deficiency Symptoms in Dogs

True vitamin C deficiency is rare in dogs. This because dogs produce enough vitamin C by themselves. Even with some liver damage, dogs appear to produce their own vitamin C sufficiently. However, severe hepatic necrosis and chronic hepatic insufficiency can cause a deficiency. This is because the liver produces vitamin C – if the liver cannot function correctly due to a chronic condition, the production of this essential vitamin decreases. Because dogs make their own vitamin C, the effects of a true deficiency are not often written about.


Because vitamin C is necessary for iron absorption, those with a deficiency are more prone to bleeding. Furthermore, the connective tissue defects caused by the deficiency cause bruising, petechiae, internal bleeding, spontaneous bleeding, and impaired wound healing. It also leads to capillary fragility. Vitamin C provides tensile strength to newly-formed collagen. Without this, new tissue cannot stretch without tearing.

The vitamin is also necessary for optimal immune function. This is a problem for animals with open wounds. Without a functioning healing mechanism and a weak immune system, pre-existing wounds are more prone to damage and bleeding. Problems with excessive bleeding aren’t always due to vitamin C deficiencies. Other causes include:

  • Hypofibrinogenemia
  • Dysfibrinogenemia
  • Disseminated intravascular coagulation
  • Factor II (prothrombin) disorders

Bone weakness

bone weakness in dogs
Canine hypertrophic osteodystrophy is a disease possibly caused by vitamin C deficiency.

Bone weakness due to vitamin C deficiency is not well studied in dogs due to its rarity, but canine hypertrophic osteodystrophy presents with bone weakness as a major symptom.

Canine hypertrophic osteodystrophy (HOD) is a disease with an unclear cause. Possible causes include vitamin C deficiency, vitamin D deficiency, excess supplementation, and canine distemper virus. There is not yet a consensus on the true cause of HOD. However, vitamin C deficiency has not been completely ruled out either. Due to this, some veterinarians prescribe vitamin supplements to affected dogs. HOD causes bone weakness, microfractures, swelling, and necrosis. In severe cases, affected dogs are unable to walk and present with pseudoparalysis.

In humans, severe vitamin C deficiency causes bone weakness. Along with this, it causes osteopenia of the long bones, delayed bone age and dense zone of provisional calcification. Swelling is also apparent along the shafts of the long bones. Pseudoparalysis is another sign of more advanced bone weakness. These symptoms resemble canine hypertrophic osteodystrophy, which is another reason for the vitamin C theory of HOD.

Muscle weakness

In skeletal muscle, vitamin C enhances carnitine synthesis, which is necessary for energy production. The vitamin also facilitates glycogen storage. These two factors mean that vitamin C is essential for keeping the skeletal muscles functional. Not only does a deficiency cause muscle weakness, but it also results in muscle atrophy when untreated, as demonstrated in a study on mice. There is little research on the muscle weakness and atrophy of dogs with vitamin C deficiency specifically due to the rarity of the disease.

However, it should be noted that hepatic necrosis is a potential cause of vitamin C deficiency in dogs. The symptoms typically include general weakness, muscle pain, and muscle stiffness. Dogs suffering from hepatic necrosis sometimes struggle to stand due to weakness or may refuse to move at all.

5 Best Vitamin C supplements

It is important to check with your vet before using any supplements for your dog. Do not forego traditional treatments. It is not always possible to correctly diagnose your pet’s problem from home, and vitamin supplements sometimes aggravate pre-existing conditions. For this reason, it’s vital that you only use supplements as they were intended – as supplements, not as substitutions. With that being said, there are several factors to consider when choosing a supplement:

  • Be wary of bold claims. This includes promises to alleviate illnesses like cancer and parvovirus.
  • Look for certification. Do any organizations approve this product?
  • What form does the supplement come in? Does your dog prefer tablets or powder?

1. Wholistic Pet Organics Ester-C Supplement

Wholistic’s Ester C uses a non-acidic, “body-ready” form of vitamin C. 1200mg of calcium ascorbate is the active ingredient of this supplement. For dogs weighing 2-30 lbs, the recommended dose is 1/4 a teaspoon. Dogs weighing 31-60lbs may have 1/2 a teaspoon. For the 61lbs or more, 3/4 a teaspoon.

This product is long-lasting and good value for money. The standard 6 oz container lasts for around 72 days, depending on the dose you give to your dog. Calcium ascorbate is a buffered form of vitamin C. It’s gentler on the stomach than pure ascorbic acid. The powder form of this product also allows for flexible dosing. It’s also ideal for pets who refuse to swallow tablets. The addition of calcium to the product also offers additional health benefits.

One reported issue with this product, according to buyers, is that it occasionally causes gastrointestinal upset. This includes diarrhea and vomiting. If diarrhea occurs, reduce the dose or discontinue use.

2. Rx Vitamins for Pets BIO-C for Dogs & Cats

BIO-C is made with sodium ascorbate 500mg and lemon bioflavonoids 20mg. The suggested dose for dogs is half a scoop of powder per ten pounds of body weight. This is to be given twice daily.

Sodium ascorbate is milder than ascorbic acid and less acidic. This makes the product more stomach-friendly than pure vitamin C. Furthermore, the additional bioflavonoids offer further benefits. Citrus bioflavonoids provide antioxidant action and boost the action of vitamin C. Buyers report that BIO-C helps their pets with ear infections and allergies.

Higher doses of BIO-C can lead to soft stools or diarrhea. Start with smaller doses, to begin with. If soft stools occur, reduce the dose or discontinue use.

3. Wholistic Pet Organics Canine Complete Multivitamins

Complete Multivitamins is an all-in-one supplement containing a wide array of vitamins, minerals, enzymes, essential fatty acids, antioxidants, and digestive microflora. This multivitamin product contains a wide range of healthy ingredients. This includes organic kelp, organic flaxseed, pineapple extract, dried papaya, and dried Bacillus fermentation product.

Most buyers of this product agree that it works well for their pets. Owners who give their dogs home-cooked food report that it offers a full range of vitamins and minerals. Most dogs find the flavor appetizing. This supplement is approved by the NASC (National Animal Supplement Council).

Some buyers report side effects of diarrhea and vomiting. This product also contains dried garlic. Dried garlic is toxic to dogs in large amounts. While this product does not appear to cause garlic toxicity, it should still be given with caution. Do not intentionally go over the recommended dose for your pet.

4. Nutrition Strength Vitamin C for Dogs

Nutrition Strength Vitamin C is made with ascorbic acid, coenzyme Q10, zinc, and selenium. The product contains 120 chewable tablets. For pets weighing less than 25 lbs, one tablet is given daily. For 26 – 50 lbs, the dose is two tablets. Dogs weighing between 51 – 71 lbs may have three tablets. Finally, dogs weighing over 76 lbs are given a maximum of four tablets.

This supplement offers a range of beneficial ingredients. Coenzyme Q10 aids energy production. Zinc supports a healthy immune system. Selenium helps to protect the cells from oxidative stress. Overall, these additional elements offer plenty of extra health benefits. Nutrition Strength Vitamin C for dogs also comes in an appetizing chicken flavor.

Two issues are brought up by buyers. One, the price, and two, the tablet form. While some dogs will swallow tablets, others refuse to try them. Although no diarrhea or vomiting has been reported, ascorbic acid can be harsher on the stomach than other forms of vitamin C for dogs.

5. Llyod & Lucy’s Pet Supplies Joint Supplement with Vitamin C

Lloyd & Lucy’s Best Value Glucosamine contains a helpful array of nutrients. These include 600mg of glucosamine, 300mg of MSM, 250mg of chondroitin sulfate, 100mg of sodium ascorbate (vitamin C) and 5mg of manganese. The inactive ingredients include silicon dioxide, pork liver powder, and microcrystalline cellulose. These chewable tablets are also liver flavored.

Many buyers report satisfaction with this product. Dogs appear to enjoy the liver taste, and the company offers a 45-day money-back guarantee if your dog doesn’t like the product. Some owners also report improvement in their dog’s joint health due to giving this supplement.

The most common issue with this product is tablets arriving broken. For some buyers, the product arrives completely disintegrated. It is also difficult for some owners to break tablets into pieces because of their fragility.

Vitamin C For Dogs – FAQs

Have any more questions about vitamin C for dogs? Feel free to browse our Frequently Asked Questions section for the answers you need.

Can I Give My Dog Human Vitamin C?

Dogs can be given human vitamin C supplements. However, using them is a risk. It is much safer to use vet-approved dog vitamins. Vitamins for humans are produced to contain 100 percent of the daily amount we require. Dog vitamins, on the other hand, typically contain a portion of this amount. This means that it’s possible to give your pet too much of a vitamin by using human supplements.

human vitamin c for dogs
It is best to use vet-approved dog vitamins.

Vitamin C in excess causes diarrhea, nausea, and vomiting in dogs. If you want to give your pet the safest amount of a supplement, you should stick with a veterinary vitamin supplement manufactured specifically for dogs. Furthermore, human vitamins sometimes contain harmful additives. For example, gummy vitamins contain xylitol, which is toxic to dogs.

How Much Vitamin C Does a Dog Need?

Healthy dogs produce all the vitamin C they need. To be more specific, it’s been found that dogs synthesize a mean concentration of 35·9 μmol l−1(range 18·2–50·7). There is no significant variation between dog breeds. There is also no variation between males and females. This means that most healthy dogs do not require vitamin C supplementation.

There is no set dose of vitamin C for dogs. Different manufacturers recommend different doses. Regardless of this fact, it’s important to stick to the dose recommended by the manufacturer. Some vitamin C for dogs is produced with additional ingredients. Accidentally giving too much of an ingredient can cause adverse effects. Always read the label carefully. If in doubt, ask your veterinarian for guidance.

Do Puppies Need Vitamin C?

Simply feeding your puppy a high-quality, balanced pet food should provide the nutrition they need. This includes vitamin C, as much of their supply is made in their own bodies. It’s also important to note that it’s easy to overdose a puppy on vitamins. Giving additional vitamins can do more harm than good. If you are concerned about your puppy’s health, always ask your veterinarian for advice.

vitamin c for puppies
A high-quality balanced pet food is enough for your puppy.

How do Dogs Make Their own Vitamin C?

Dogs produce vitamin C in the liver. The production of vitamin C depends on the liver microsomal enzyme L-gluconolactone oxidase. L-gluconolactone oxidase gives the ability to synthesize vitamin C from monosaccharides. It does this by catalyzing the reaction of L-gulono1,4-lactone with oxygen to L-xylo-hex-3-gluconolactone with hydrogen peroxide. The resulting enzymes are able to convert to vitamin C spontaneously. Humans and some other animals lack L-gluconolactone oxidase, which renders them unable to synthesize their own vitamin C.

Vitamin C for dogs has several advantages and disadvantages that owners should consider. It’s important to consider your dog’s health status before giving any supplements, and this includes vitamin C. As with any additional supplements, you should seek veterinary advice before beginning any treatments at home.

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