Should I Give My Horse Vitamin C? A Vet's Guide

Wondering if you should give your horse vitamin C? Most healthy horses don't need extra, because they make their own in the liver. A supplement may help in specific situations, such as older age, illness, prolonged stress or heavy work. Always check with your vet before starting, because the right call depends on your horse.

Do Horses Need Vitamin C?

Healthy horses don't need vitamin C from their diet.

Unlike people, horses make it from glucose in the liver, and healthy horses normally produce an adequate amount. In the body, vitamin C is an antioxidant that supports the immune system and helps build collagen, the protein that gives skin, tendons and other connective tissue their strength.

So why does the question keep coming up? Production has limits. Researchers note that prolonged stress can use up vitamin C faster than the liver replaces it. That is the gap a supplement tries to fill, and it is why a healthy horse on a good diet usually doesn't need one.

When Should You Give Your Horse Vitamin C?

Vitamin C is most likely to help when a horse is under ongoing stress or dealing with a health problem, and your vet is the best person to say whether that's your horse. Situations that vets and researchers commonly discuss include:

• Senior horses, particularly those with pituitary dysfunction (PPID), where vitamin C has been looked at for immune support.
• Long periods of stress, such as extended travel, a busy competition run or chronic illness.
• Hard training, where demand for antioxidants can rise.
• Respiratory problems, where antioxidant support has been explored for horses with heaves.

Opinions differ on how much each of these matters. The evidence is still limited, and no two horses have the same age, workload, diet or health history. That is why a vet's assessment counts for more than any general rule.

A horse on a balanced diet with good grazing is in a different position from a horse in hard work, recovering from surgery or living with a long-term condition. Your vet can look at the whole picture, including your horse's feed, workload and health history, and run tests if needed. Only then does it make sense to decide whether a supplement has a place.

Hot weather is a separate topic. Our guide to heat stress when training and competing covers cooling and hydration, and electrolytes for horses are usually part of that plan. If you compete, ask your vet about any supplement rules before adding a product.

Can Too Much Vitamin C Be Harmful?

Vitamin C is water-soluble, so any excess is mostly passed in urine. That means extra is more likely to be wasted than to cause harm, which also makes it a poor use of your budget for a horse that doesn't need it.

The bigger question is your horse's own supply. Researchers suggest that supplementing for a long time may dampen natural production, so levels can sit lower for a while after a course stops. That's one reason vitamin C is usually given as part of a plan.

Not all forms are equal either. Some are absorbed better than others, and individual horses respond differently. Your vet can recommend a form that suits your horse.

It also pays to check the labels on any feed or multivitamin your horse already receives. Knowing what's in the bucket today makes it easier for your vet to judge whether anything extra is needed.

How to Give Your Horse Vitamin C

Vitamin C for horses is usually given as a powder or oral supplement mixed through feed. You can browse our oral supplements to see what's available.

Healthy horses have no set requirement, so there's no single dose that suits every horse. Researchers generally favour short courses tied to a stressful event, and caution against prolonged supplementation. The amount, the form and how long to give it all depend on why you're using it. Before you start, ask your vet:

• Does my horse need it?
• Which form, and how much?
• How long should I give it, and how do we wind it down?

Your vet can write a plan around your horse's age, workload and health.

Talk to a Scone Equine Vet

Not sure whether your horse needs vitamin C or another supplement? Our vets can look at your horse's age, workload, health and diet, then recommend a plan that fits. Contact the Scone Equine Group team or browse horse vitamins and supplements in our online store.

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