SmartPak Smart & Simple Magnesium Oxide Powder Horse Supplement, 3-lb bag

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($0.26 /serving)
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About This Item

Details

  • This supplement provides 5,000 mg. of magnesium oxide per serving.
  • You’ll be happy to know that magnesium oxide can help promote a calm demeanor in horses.
  • Plus, this useful supplement also supports healthy muscles.
  • Help your horse maintain proper metabolic and nervous system function with this supplement.
  • This powder horse supplement features one main ingredient for simple and effective supplementation.

Ingredient Information

Feeding Instructions

Learn More About SmartPak From Our Team of Experts

Questions & Answers

2 Customer Questions


What is the shelf life of magnesium powder


How many days is each bag

Answer by ChewyJun 25, 2025
There are approximately 154 servings per 3-lb bag and about 515 servings per 10-lb bag.
4.8
Rated 4.8 out of 5 stars
71 Ratings

35 Customer Reviews



Rated 4 out of 5 stars
Received Free Product
By Opalsmomma on Jun 8, 2026

Just started and already seeing a difference.

My mares often full of anxiety and works hard but gets sore. She's been on this 5000mg dose of magnesium for a week and seems calmer in her stall. She even stayed

My mares often full of anxiety and works hard but gets sore. She's been on this 5000mg dose of magnesium for a week and seems calmer in her stall. She even stayed in no screaming and pacing for an hour by herself. Something she usually can't do. We tried this supplement as it is said magnesium can have a calming effect, but mostly we wanted to be sure her muscles were getting enough as she's been girthy lately and just a bit stiff. Shes a teen now so we want her to last and years ago magnesium helped my old horse when she was just moody so didn't have anything to lose. We've only been using for a week. It's easy to measure, and when added to her grain she eats it no issues but we do as water to her meals as that's her preferred way to eat


Rated 5 out of 5 stars
Received Free Product
By Patty B on Jun 11, 2026

Easy to Use Smart & Simple Magnesium Powder

This Smart & Simple Magnesium powder has helped my horse with his nervousness. It has also helped with his muscles. It has 5,000 mg of Magnesium Oxide. It's an easy

This Smart & Simple Magnesium powder has helped my horse with his nervousness. It has also helped with his muscles. It has 5,000 mg of Magnesium Oxide. It's an easy to administer powder that I use on his food at night. 1 scoop is all he needs.


Rated 5 out of 5 stars
Verified Purchase
By Megan on Jul 30, 2025

So cost effective

Got 10lbs for the price of two months of this from SmartPak! Set for over a year for such a good price. I also like that this provides the same amount of magnesium

Got 10lbs for the price of two months of this from SmartPak! Set for over a year for such a good price. I also like that this provides the same amount of magnesium in a much smaller scoop than other brands that I have used, less powder in her food = happier pony! It would be better if this came in a tub instead of a zip bag (I don’t think it would hold up for over a year of opening and closing every few weeks, I prepack my own supplements) so I did have an old container that had powder in that I dumped this into


Rated 5 out of 5 stars
Received Free Product
By Crystal on Jun 12, 2026

Smart equine magnesium

This product is great for our rescue horses ,magnesium is vital for so many body functions. It arrived quickly.The horses gobble it right up and it mixes well with

This product is great for our rescue horses ,magnesium is vital for so many body functions. It arrived quickly.The horses gobble it right up and it mixes well with their grain,very good product.


Rated 5 out of 5 stars
Received Free Product
By RW92 on Jun 14, 2026

PSSM1 mare likes it!

Magnesium was recommended for my PSSM1 mare. She eats this with no problem mixed in her ration balancer. So far, I haven’t noticed any adverse effects. Packaged

Magnesium was recommended for my PSSM1 mare. She eats this with no problem mixed in her ration balancer. So far, I haven’t noticed any adverse effects. Packaged well and looks fresh.


Rated 5 out of 5 stars
Received Free Product
By Horseshoes on Jun 7, 2026

So far so good!

So I don’t think my horse has really been using this product long enough to give a complete review. However, I will say he takes it easily in his grain and doesn’t

So I don’t think my horse has really been using this product long enough to give a complete review. However, I will say he takes it easily in his grain and doesn’t mind the taste. He can be very energetic at times, and the last few rides since using this product have been easier and more contained. So I’m going to give the credit to this supplement and hope the behavior continues.


Rated 5 out of 5 stars
Received Free Product
By Mari on Jun 29, 2026

I think it is making my tense horse calmer

My vet recommended magnesium to help calm my new, young OTTB. My trainer and vet have been helping him to recover and to get back to work after a serious injury

My vet recommended magnesium to help calm my new, young OTTB. My trainer and vet have been helping him to recover and to get back to work after a serious injury. Before we started him on the magnesium he was very tense and reactive. It seems to be helping him to relax more.


Rated 5 out of 5 stars
Received Free Product
By Hamy on Jun 29, 2026

Love this supplement!

Love this magnesium supplement. My picky mare doesn't even notice I have added this to her food but I definitly notice! She is calmer and I have noticed a slight

Love this magnesium supplement. My picky mare doesn't even notice I have added this to her food but I definitly notice! She is calmer and I have noticed a slight improvement in her overall disposition, which is saying a lot for my red mare.


Rated 5 out of 5 stars
Received Free Product
By Tricia on Jun 9, 2026

Great Magnesium Supplement

I am so happy that Chewy is carrying these products! I have always been a believer in Magnesium as a supplement that helps with muscle relaxation and recovery

I am so happy that Chewy is carrying these products! I have always been a believer in Magnesium as a supplement that helps with muscle relaxation and recovery. This is a great powder that is highly palatable and so easy to sprinkle on her daily grain.


Rated 5 out of 5 stars
Received Free Product
By EllieUki on Jul 14, 2026

Very helpful during the summer months

This has been really helpful for my horses during the hot Florida summer. It mixes easily into their feed, they eat it without any issues, and they seem to be doing

This has been really helpful for my horses during the hot Florida summer. It mixes easily into their feed, they eat it without any issues, and they seem to be doing well on it. I’m happy to have it as part of their summer routine.