Vitamin A for horses

Hay bales in a field representing the importance of Vitamin A for horses
Vitamin A is a crucial fat-soluble vitamin for horses, playing a vital role in their overall health and well-being. While horses that have access to green forage can obtain sufficient Vitamin A through carotene conversion, those fed poor quality roughage or lacking access to green forage may require supplemental Vitamin A. However, it’s important to be cautious of potential toxicity when supplementing Vitamin A in addition to a well-fortified grain base. This article will explore the role of green forage, causes of Vitamin A deficiency, and total dietary requirements for horses of different activity levels and life stages.

Role of Green Forage in Meeting Vitamin A Requirements

Green, leafy roughages provide carotene, which horses can convert into Vitamin A. However, bleached, weathered, or dark and dusty roughages do not contain sufficient vitamin content. When horses have access to good quality green forage, they can generally meet their Vitamin A needs. But if a horse is fed poor quality roughage, supplementation becomes necessary.

Causes and Symptoms of Vitamin A Deficiency in Horses

Many horses experience Vitamin A deficiency due to consuming hay stored for extended periods. Commercially prepared grains often include Vitamin A to address this deficiency. However, it’s essential to avoid overdosing horses with high-potency vitamin supplements when they are already receiving well-fortified grains.

The signs of Vitamin A deficiency in horses include dry, scurfy skin and hair coat, runny eyes, and night blindness. Studies have shown that night blindness can be induced by Vitamin A deprivation and reversed by adding sufficient Vitamin A back into the diet. Other symptoms may include dry and scaly hooves, increased susceptibility to respiratory infections, stress, and diarrhea. Toxicity symptoms may include dry hair, anemia, and increased bone size.

Total Dietary Requirements for Horses

According to the 2007 NRC Guidelines, the total dietary Vitamin A requirements for an 1100lb horse are as follows:

– Maintenance horses: 15,000 IU per day
– Moderately active horses: 22,500 IU per day
– Pregnant/lactating mares: 30,000 IU per day

Additional Vitamin A is crucial during the last 90 days of pregnancy, lactation, and for high-performance horses and weanlings.

Vitamin A plays a vital role in the health and well-being of horses. While green forage can meet their Vitamin A requirements through carotene conversion, horses fed poor quality roughage or lacking access to green forage may require supplemental Vitamin A. It’s important to be cautious of potential toxicity when supplementing Vitamin A on top of a well-fortified grain base. By understanding the causes and symptoms of Vitamin A deficiency, horse owners can ensure their horses receive adequate nutrition for optimal health and performance.

At Nutrena, we believe proper nutrition plays the biggest role for a lifetime of health and happiness for every horse. That’s why Nutrena horse feeds are specifically formulated for every life stage and activity level. 
Learn more about our feeds formulated specifically for hard keepers to ensure your horse is getting the optimum nutrition  to maintain their weight and health at feeding time, every time.
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15 Replies to “Vitamin A for horses”

  1. I have a question about Vit A. I have a mare that foaled on June 6th. Her foal and another mare of mine are showing signs of having a Vit A deficiency, what kind of feed do i look at getting for my herd to help supplement them in this vit? I know now why they are deficient, we have a coverall barn that bleaches all my hay.

    1. Hi Cassandra, Great question. We would suggest looking for a complete feed that is designed specifically for mares & foals – something like SafeChoice Original, or Life Design Mare & Foal. These will both have added Vitamin A, specifically to help combat low levels in hay that has been stored for a while. Thanks!

    1. Hello Claire, Thanks for the question. Yes, horses can develop toxicity situations with Vitamin A, because it is a vitamin that is stored up in their fat reserves.

      According to 2007 NRC Guidelines, the Total Dietary (ie. Hay + Grain) Requirements for 1100lb horse are:
      15,000 IU per day for maintenance horses
      22,500 IU per day for moderately active horses
      30,000 IU per day for pregnant/lactating mares

      Thank you ~ Gina T.

  2. I have a older miniature horse that is diagnosed with uvitits. I was wondering if I should start giving him vitamin A. He doesn’t weigh anywhere near 1,100 lbs he weighs more 350lbs. What would be the correct daily dosage at his weight?

    1. Hi Monica, We strongly recommend working with your vet before making any dietary changes in relation to a diagnosed condition. Your vet will be able to tell you if dietary changes will affect his specific condition. Thanks! Gina T.

    1. Hello Julie,

      Thanks for the question. This is where tags can be confusing – they require a little math to compare “apples to apples”. This particular supplement is listed in IU/kg. Most feeds list vitamins in IU/lb. You also have to consider that this is a supplement, of which you feed a tiny 1 oz (30 grams) scoop per day. If you follow the math down from the IU/kg to a 30 gram dose, it provides 33,000 IU of Vitamin A per day – provided you follow the one scoop daily dose recommendation.

      Compare this to a feed, which might be listed at 4,000 IU/lb. If you follow the directions and feed 6 lbs per day of the feed, then you are providing 24,000 IU of Vitamin A per day.

      Considering the minimum daily requirement for a 1100 lb horse in maintenance is just 15,000 IU per day, and the same horse in high exercise is around 30,000 IU/day, and you haven’t yet included Vitamin A from forage, most feeds provide plenty of the needed Vitamin A and supplements are not likely required.

      We hope this information is helpful! Thank you ~ Gina T.

  3. Just wondering how much Vitamin A is in a pound of carrots, since i feed as a treat daily.

    1. Hi Paula,
      Great question! Carrots are a good source of Vitamin A and will contain about 15,000 IU/pound. This is provided as beta carotene, which is why the carrots are orange. The horse converts the beta carotene into Vitamin A. The average carrot weighs about 61 grams or about 2.15 ounces. The average 61 gram carrot also contains about 2.9 grams of sugar, about 4.75% sugar. One reason horses like them!
      Best of luck!
      Roy J.

  4. I have a horse with pigeon fever it started with swelling in the belly then up into the sheath, this has gone for 4 months, there abcesss inside the sheath that have drained occasionally, I’ve kept him on bute for the last 3 months, it has become huge and hard in the sheath and hot to touch, I’ve read that vita A is something lacking in horses with pigeon fever, what is your thought, since one horse out of a pasture of 3 or horses may get pigeon fever and the rest don’t! Is this deficiency issue possibly! Thank you Tamey

    1. Hi Tamey,

      Thank you for your question regarding Vitamin A deficiency and Pidgeon Fever. Pidgeon Fever is an infection caused by Corynbacterium pseudotuberculosis. The bacteria frequently enters the animal thru scratches or fly bites. If you look on line, the American Association of Equine Practitioners (AAEP) has a very good article on this disease. Vitamin A is one of the many nutrients that are involved in skin integrity and immunity. We would not expect Vitamin A deficiency to be linked directly to a bacterial disease. Because there are multiple nutrients that contribute to skin integrity and immune support, a feeding program that provides these nutrients would always be appropriate. If your horses are on pasture, you may want to consider using a ration balancer that would help make certain the horses are receiving appropriate vitamins, minerals and amino acids for health skin and for immune support. Pidgeon Fever is not considered contagious, but could be spread by direct contact or biting insects.

      We would recommend that you work with your veterinarian to determine if treatment is required as this will vary case by case.

      Best wishes,

  5. My 25yr old gelding was underweight when i got him about a month ago. He cannot eat grass or hay due to worn down back teeth. I also have noticed he has trouble seeing at night with a blue ring around his iris. Ive been noticing dry hair and some patchy hair loss in small amounts mostly on his face. Ive been feeding him 12lbs of safe choice senior since i received him. He was gradually worked up to that amount 4lbs 3x a day. Is it possible that he is missing out on something nutritionally eventho he is eating a complete feed? His basic blood work came back normal. He seems appendix type and is about 15.3 and weighs under 1000lbs. Any suggestions or ideas? He looks pretty good otherwise eventho i feel he could use a bit more weight.

    1. Hi there! It’s going to take some time to reestablish nutrient levels in his body, but you are on the right path! I would recommend increasing his Nutrena SafeChoice Senior to 15-18# per day in total. He can very safely consume larger meals of this particular product. I might also recommend adding 1#/day Nutrena Empower Topline Balance for 30-60 days to aid in his rejuvenation process.

      Keep up the great work!

      -Abby K.

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