Vitamin C for Dogs: Functions, Recommended Intake, and More

You’ve probably heard that you should up your vitamin C intake when you’re sick, but do you know why that is? Vitamin C (or ascorbic acid as it’s also known) is crucial for normal immune function in mammals, dogs included.

But what is the daily recommended intake of vitamin C for dogs? Should you be giving your dog a vitamin C supplement? We’ll discuss this, as well as signs of deficiency and overdose, to help make sure your pup is getting exactly what they need. 

Vitamin C is essential for a healthy immune response since it promotes the activation of white blood cells, the body’s principal means of fighting infection. What’s more, it boosts the body’s natural defensive mechanisms by stimulating the release of interferons, which are proteins that help prevent cancer and other diseases. Vitamin C also has antioxidant properties, protecting the body from dangerous free radicals and premature aging.

So what else does vitamin C do for dogs? Let's take a look!

• Promotes the development of healthy skin and bones through the production of collagen.
• Assists in hormone and vitamin E production.
  
• Protects against cancer and other diseases.
  
• Prevents the formation of bladder stones.

Unlike humans, who must get vitamin C from their diet, dogs can synthesize their own vitamin C. The Association of American Feed Control Officials (AAFCO) nutrient profiles for dogs don't include requirements for vitamin C in dog food.

Keep in mind that seniors, growing dogs, and pregnant or lactating bitches need additional vitamin C. Ask your vet the exact amount your dog should be receiving.

How much vitamin C can dogs make per day?

In a normal, healthy state, dogs make about 18 milligrams of vitamin C for each pound of body weight, which is typically enough to meet their needs. Exhaustion, emotional stress, hard working conditions, and other diseases can deplete vitamin C stores, causing dogs to need dietary supplementation.

Most dog food manufacturers fortify their blends with vitamin C not just because it’s good for dogs, but also because it acts as a preservative. While commercial dog foods often contain all the vitamin C that dogs need, other dog-safe fruits and veggies pack a healthy dose of this essential nutrient, including:

• Asparagus
• Broccoli
• Brussels sprouts
• Kale
• Oranges
• Cauliflower
• Carrots
• Apples
• Melons
• Peaches
• Apple cider vinegar

Because they can synthesize their own vitamin C, deficiency is extremely rare in dogs. One of the first studies on vitamin C in dogs, published in 1931, found that 5 puppies fed a vitamin C-deficient diet showed no changes in health or wellness after 150 days.

So what happens in the rare event that dogs become vitamin C-deficient? Like humans, dogs can get scurvy from lack of vitamin C in the diet. Though rare, this condition is more likely in young dogs than adults. Scurvy can be deadly if left untreated, so it’s important you see a vet immediately if your dog has any of these symptoms:

• Foul breath
• Weakness
• Swollen or bleeding gums
• Slow wound repair
• Joint pain
• Soft bones
• Frequent bone injuries

Treatment of vitamin C deficiency

Again, vitamin C deficiency in dogs is rare, but is usually treated with supplementation. Vitamin C supplements may be given orally or intravenously.

What causes vitamin C deficiency in dogs?

Apart from a nutritional deficiency, other conditions can affect your dog's vitamin C levels. Several veterinary studies found low and deficient levels of vitamin C in dogs diagnosed with sarcoptic mange, bloat (GDV), and a bacterial infection called visceral leishmaniasis.

More research is needed to determine how the severity of a condition influences the body's production of and ability to absorb vitamin C.

Since vitamin C is water-soluble, overdose is rarely an issue. A dog will ordinarily excrete any excess vitamin out in their urine. Occasionally, over-supplementation of vitamin C can lead to diarrhea in dogs.

Some dog parents turn to supplements when they feel like their pet isn’t getting enough vitamin C. But healthy dogs eating a commercial kibble that's already fortified with vitamin C probably won’t respond to supplements.

That said, some dogs with underlying conditions respond quite well to supplements, and some vets prescribe them for certain illnesses.

Which dogs benefit most from vitamin C supplements?

Pregnant dogs may need more vitamin C for developing fetuses since pregnancy can hinder vitamin C synthesis.  

Supplementing with vitamin C is especially beneficial for older dogs with arthritis, and often, vets will recommend high doses of as much as 2,000 milligrams or more for this purpose. Some vets also recommend vitamin C for dogs with hip dysplasia. 

Vitamin C can help with urinary tract problems as well. Vitamin C lowers the pH of urine, which can help prevent the formation of bladder stones in dogs. Due to its antihistamine-like properties, vitamin C may also help dogs with allergies.

Can I give my dog human vitamin C supplements?

It's always best to consult your vet before giving your dog any over-the-counter medications, especially those formulated for human use. Since vitamin C is water-soluble, overdose is extremely rare, but human medications can contain other ingredients that are toxic to dogs. If you have questions about vitamin C supplements for your pup, please consult your vet.

Can vitamin C supplements help treat other conditions in dogs?

Yes! According to a 2020 study on vitamin C in companion animals, vitamin C supplementation has been used as an experimental treatment for hip dysplasia, bone inflammation, and maintaining fluid levels in burn patients. However, studies on its efficacy as a treatment for other conditions is limited.

As you can see, vitamin C has some pretty extensive effects on the canine body. While kibble usually has all the vitamin C dogs need that dogs can't synthesize themselves, some pet parents choose to give their dogs vitamin C for an extra boost. While this probably won’t show any immediate difference in healthy adult dogs, it may prevent certain conditions like bladder stones later on.

Contact your veterinarian immediately if you suspect your pup has a vitamin C deficiency.