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Should you give your dog Vitamin C?

Should you give your dog Vitamin C?Dogs are like people in a lot of ways. They are part of our family. Many diseases that people get, dogs can get. We even treat dogs with many “human” medications!

So it’s easy to see how the line can be blurred on where the dog-human similarities end. One big difference is in the area of vitamin supplements.

People take Vitamin C supplements commonly. Feel a cold coming on? Sat next to a person who was sneezing? Flu season is here? Time to grab the vitamin C! Since it helps our immune system, then shouldn’t we give it to our dogs?

The short answer is NO! Here’s why.

When it comes to being able to synthesize our own vitamin C, people suck. We just can’t do it. Our bodies can do a lot of things, and synthesize a lot of different vitamins and nutrients. Unfortunately, we missed the boat on manufacturing Vitamin C. Apes, who are closely related to human beings, also lack this skill.

Most other animal can manufacture their own Vitamin C, so supplementing is not necessary. Dogs, cats, horses, all can make their own vitamin C, and can make as much as their bodies need.

(BUT, there is another pet that cannot make Vitamin C and must have it supplemented. Know what it is? Tell ya later…)

So if a dog’s body is fully able to meet all of its needs for Vitamin C, there is no need to supplement it. OK, but it is a water soluble vitamin, and extra gets eliminated in the urine, so can it really harm your dog?

It can! Particularly if your dog is a growing puppy!

Excess Vitamin C causes blood levels of Calcium to rise. This causes an increase in a hormone called calcitonin. It basically detects the abnormally high levels of Calcium in the blood and tries to come to the rescue. This results in two very bad things in a growing puppy. It inhibits the growth and maturation of cartilage. Cartilage is very important for joint health, so affecting the development of cartilage in a puppy can lead to a lifetime of arthritis and joint problems.

The increase in Calcium, and resulting action of calcitonin, also affects the body’s ability to remodel and reshape bones as they grow. This is particularly important in large breed puppies, whose bones are growing and remodeling at a very rapid rate. It’s been demonstrated in studies that puppies with excess calcium in their bloodstream are highly likely to have profoundly abnormal joints when they grow up.

So why would you give your dog something that A) he does not need and B) can cause him harm??

Take the Vitamin C for yourself. Don’t give it to your dog!

(BTW – the pet that cannot make its own Vitamin C – guinea pigs!)

Web-DVM guest blogger Dr. Karen Louis is a practicing small animal veterinarian.  See more of her articles at her blog at

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