Feeding HYPP Horses

HYPP horses need low potassium diets when compared to “normal” horses – less than 1% potassium in total diet including hay + grain.  But, a percentage in a feed is really only a percentage and doesn’t tell you what you really need to know – which is, how much potassium your horse is actually getting in the total diet.  This number will depend on the percent of potassium in each feedstuff, and how much of each feedstuff is being fed. 

Hay Selection:  Hay makes up the majority of the diet so typically contributes the most potassium. It’s best to have your hay tested if possible, but if you can’t do that, keep in mind the following:

  • Oat hay and grass hay are the lowest in potassium
  • Orchard grass is high in potassium so stay away from that.

Feed Selection:

  • Textured/whole grain based feeds tend to be lower in potassium then pelleted feeds, since whole grains are naturally low in potassium, where some ingredients used in pellets tend to be higher potassium sources.
    • “Sweet” feeds may or may not use a lot of molasses, which is high in potassium. The “wetness” of a sweet feed may come from vegetable oils rather than molasses, so don’t automatically rule sweet feeds out. 
    • Some pelleted feeds can be a good choice if the horse is N/H and doesn’t have many episodes, but may not work for horses that are H/H and have severe or many episodes.   
  • Higher fat and calorie feeds may allow you to feed less, and this can lower total potassium as well when you can feed less to maintain body condition.
  • Do not feed electrolytes containing potassium. 
  • Do not use high levels of cane, molasses, or bran mashes because they may be high in potassium.

Doing the math: To determine how much potassium is in your HYPP horse’s total diet, you’ll need to do some good old fashioned math!

To check for total potassium in the diet:

(Pounds of hay x percent potassium in hay) + (pounds of grain x percent potassium in grain) / total lbs of feed

Example: If you feed 15 lbs of hay at 1% potassium and 6 lbs of grain  at 0.8% the calculation would be:

((15 x .01) + (6 x .008))/21 lbs of total feed = 0.942% potassium in total diet

From this example, the horse should do well on this diet.  If the horse can maintain body condition on less hay or grain, or if the hay tested lower in potassium, then that would be less potassium in the total diet as well. 

Other Considerations:

  • Starch Intake: It is a misconception that HYPP horse need low starch.  They actually need sufficient starch as a source of glucose, because glucose stimulates the release of insulin and this promotes potassium uptake by the cells.
  • Management:  HYPP horses should be turned out as much as possible and/or placed on a regular exercise program. 

30 Replies to “Feeding HYPP Horses”

    1. Hello Patricia, Thanks for the question! Our lowest potassium feed that we recommend for HYPP horses is ProForce XTN. XTN is 12% fat and high in calories.

      Higher fat and calories allow you to feed less than other feeds, and this can lower total potassium as well when you can feed less to maintain body condition. These is a textured feed, and textured feeds tend to be lower in potassium then pelleted feeds. We have several halter horse farms that use these products for their show horses with HYPP. For pelleted feeds, SafeChoice Original can be a good choice if the horse is N/H and doesn’t have many episodes. We do not recommend SafeChoice Original for horses that are H/H and/or have severe or many episodes. Some horses on acetazolamide have done well on SafeChoice Original. It really depends on the individual horse and the severity of the episodes if any and management is key for HYPP horses as well.

      Keep in mind as well that it will also depend on type of hay you are feeding and percent potassium in hay.
      Thanks ~ Gina T.

  1. We have raised hypp n/h horses for over 16 years. We have never fed them any differently than the n/n horses and never had any problems. Even our foaling mares are fine. We feed pellets, oats, alfalfa and coastal. Too much bad publicity out there for these horses.

    1. i’m glad you haven’t had any issues. here comes the but, I didn’t either I’ve had my 2yo since he was 9 months old when I didn’t know his hypp status. he was on my growing plan of all the alfalfa he could eat and a 14% 6% fat ration . he started showing signs of attacks with his 3rd eyelid showing and roaring breathing I would give him karo and he would get better. after a couple of these I put him on acetazolamide and added salt . three months ago he had a full blown falling down dog sitting attack. I had had him on oat hay and a small amount of alfalfa , after that I doubled his ace and cut out alfalfa and he had another attack. at this time I now have a useless horse, pretty but useless no trainer will take him to ride due to the unpredictability of the attacks. moral of the story is that just because you haven’t had an issue doesn’t mean you won’t .

      1. I couldn’t agree more, Lisa. My HYPP N/H horse was on safechoice original before I even realized he had HYPP, he had a severe attack and the vet actually calls him her “miracle patient” to this day. He was completely paralyzed, only able to move his eyes. My vet actually told me to say goodbye, it was the most traumatic thing I have ever experienced and I work in healthcare. He is now on Acetazolamide 2x daily with his grain. He even had another attack while being on that so we changed his grain. He is my baby but pretty much useless because I’m scared too much stress with cause another attack. Leeann everyone has different experiences. MY horse would be dead by now if he was fed alfalfa.

  2. I have a n/h mare who’s 7. Didn’t know her testing till after I bought her. Worst thing is I loved this mare well still do. Had no problems ever with her and now I scared to ride her and she is suck a good mare. I had a gelding have a heart attack on me and went down. Dead. Totally did t see that coming. Had another fracture his seamoid bone while riding. A girl friends mare snapped her leg riding her. I just with someone would shed some positive light because I feel like I have been handed the death sentence now.

    1. Hi Denise – Sorry to hear about your run of bad luck! We would suggest following the guidelines in this blog post, and also working closely with your veterinarian to manager her condition. Many, many n/h horses have led successful careers and lives with proper management. Good luck! Gina T.

  3. I have a 7 yr old HYPP N/H mare. I have owned her since she was 3. No signs of attack until I started pushing feed/hay to get her ready for a horseshow. She started sweating,listless and signs of attack. Vet took blood samples and confirmed.she now exhibits withdrawn, weaving to the point of trance like state ,restlessness after eating.this happens, almost daily and after she eats. I feed dry cob, orchard grass and small flake of alfalfa twice a day. In summer, she only gets grass hay and still exhibits signs. She is such a sweet mare, I don’t want to let her go. What can I do?it doesn’t seem to matter what she eats, she exhibits these signs. I also keep karo on hand .

    1. Hello Laura, Thanks for the question. The big key to diets for HYPP horses is low potassium. This means less than 1% in total (hay + grain) diet and no more than 30g potassium in any given meal.

      The horse should be turned out as much as possible and/or placed on a regular exercise program. Feed oat grass or grass hay but NOT orchard grass hay, which is high in potassium. You can get your hay tested for potassium content from your hay supplier or local extension office. Other consideration are do not feed electrolytes containing potassium, and avoiding feeding high levels of soybean meal. Soybean oil, canola oil, cane molasses or bran mashes as they may also be high in potassium.

      We would recommend straight oats, grass hay and a vitamin mineral supplement for your mare.
      Thank you ~ Gina T.

  4. I’ve had my n/h for 4 years now. He’s had 4 episodes.
    1. When I first got him and the vet gave anesthesia to float his teeth and he went down. I didn’t realize he was hypp til then.
    3 at home, 2 mild and 1 bad. He only gets safe choice original and coastal hay. As long as I keep him on that and turned out he does good.

  5. I try to minimize the potassium in my HYPP mare. I just bought dry COB of a new brand and its label says it contains Potassium Bisulfite as a preservative. Should I avoid giving this to her?

    1. Hello Clarice,

      Thanks for the question! You don’t really want to focus on the specific ingredients that are the source of the potassium in the case of HYPP horses, but rather focus on the total potassium in the feed, and then in her overall diet, using the formula shown in the blog post. You will want to look at the tag and see if they guarantee the potassium level, and then do the math based on the feeding rate you would give her, to see if she will stay under that 1% total potassium in the diet target level or not. If the potassium level isn’t on the tag, then contact the feed company and they should be able to tell you. Since COB is made of straight grains, which are typically very low naturally in potassium, you may still be OK to use it.

      I hope this is helpful to you! If you have other questions, please let us know! Thank you ~ Gina T.

  6. Hello! I have a 19 year old mare who is HYHPP N/H. She was a pleasure horse until she was 16 and is now retired but she get ridden for fun and 3 days a week. She has been on strait oats, grass hay, and pasture but the oats are making her hot. She had never had an episode while in my care and her previous owners said the last one she had in their care was when she was 6yo. I have been researching feed for quite some time now. I really like the Nutrena Safe Choice Special Care, and I have read where many people with n/h horses feed it and love it, but, it contains cane molasses and alfalfa meal. I can not find the potassium content on the label. Would this be a safe switch to make? Thanks!

    1. Hello Mercede – Thanks for the question. Our lowest potassium feed that we recommend for HYPP horses isProForce XTN. ProForce XTN is 12% fat and high in calories. Higher fat and calories allow you to feed less and this can lower total potassium as well when you can feed less to maintain body condition. These is a textured feed, and textured feeds tend to be lower in potassium then pelleted feeds. We have several halter horse farms that use these products for their show horses with HYPP. For pelleted feeds, the SafeChoice feeds can be a good choice if the horse is N/H and doesn’t have many episodes. We do not recommend SafeChoice feeds for horses that are H/H and have severe or many episodes. Some horses on acetazolamide have done well on SafeChoice Original. It really depends on the individual horse and the severity of the episodes if any and management is key for HYPP horses as well.

      It will also depend on type of hay you are feeding and percent potassium in hay, of course, since hay makes up the largest percent of the diet, and thus the amount of potassium there will have a bigger impact than a few pounds of feed per day.
      Thank you~ Gina T.

  7. I just received a beautiful, 4yo gelding from my husband for Christmas. When he purchased Jake we knew going into this that he was HYPP N/H. The people we bought him from said he has never had an attack and they were feeding him alfalfa hay in the am and bermuda in the pm. Alfalfa is completely out of his diet since we have had him! We have done all the research on feeds and hay and have him on as strict of a potassium diet as possible. The only problem is that his feet could use a little help. I have tried to find a biotin supplement that would be safe for him, but everything either has linseed meal, flaxseed meal/oil, or soybean meal/oil. Do you have any recommendations? I just want to take care of him the best I can without causing him any harm.

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  9. I have a gorgeous 7 year old mare that I just found out was N/H. When I bought her 5 years ago the breeder did not mention anything about this although they knew as it was on the papers I received from the AQHA. I am really disappointed in the fact they would be so unscrupulous in withholding that kind of information just to get the price. I have had horses over the years but had never heard of this condition. I appreciate all the info out there to help manage and maybe one day eliminate this gene or at the very least minimize its presence. I have been fortunate that she has never exhibited any signs and the feeding program I have her on has been one that closely mimicks the one you recommend. Thank you for putting this data out there. In hindsight, yes I still would have purchased her –it was love at first sight for both of us. :). Just wished I had known so I could have been prepared in the event she did have an episode.

  10. I have a coming two yr old breeding stock paint filly that basically with no warning collapsed in our arena she didn’t even try to move or get up had tremors from head to toe an was scared but didn’t panic. My friend realized what was happening and said go get kayro syrup an a syringe. So we got 1oz in her an with in 30 mins she was up walking around like nothing happened it was crazy never ever seen that happen, 30 yrs in horse’s an never. We have had her test she is N/H she’s never had another attack that extreme but does tremor every so often. She’s on pasture with other yearlings and only getting grass hay basic valley grass, problem is she’s dropped 75lbs an doesn’t even look like the same filly. I’m trying to figure out a nutritional feeding program everyone says oats an grass hay but she’s growing does she need more? She was on sweet feed an alfalfa for her whole first yr until this attack, she looked great but attacks didn’t mellow out till alfalfa was discontinued an no more sweet feed. I would like to bring her up to fit her up some to possibly break her this coming spring. HYPP seems to be just swept under the rug for Breeders but for me I really love this girl an want her to have the best life. I’m lost on what to do to make sure she grows and delevopes well.

    1. Hello Beverly, Thank you for contacting us, and we fully understand you concern for your filly!

      Alfalfa is high in potassium, so is the most likely culprit behind her attack. The switch to grass hay would definitely help lower her potassium intake and reduce the severity/frequency of the attacks. To be absolutely certain about her diet, we would recommend having her hay tested, so that you can design the rest of her diet around it’s potassium content. Since hay of course makes up the majority of any horse’s diet, it will generally be the highest contributor of a given nutrient.

      Once you know the potassium level in her hay, you can work towards building her a diet that is 1.0% potassium or less, using the math demonstrated in the article above. For feeding her any kind of grain, textured feeds do tend to be lower potassium than pelleted feeds – the whole grains used in textured feeds are relatively very low in potassium compared to ingredients used in pelleted products – and a high fat level textured feed can help keep weight on better than just plain oats would.

      From the Nutrena family of products, we’d recommend using our ProForce XTN product to keep the potassium level down and the calorie level up.

      We hope this helps! If you have further questions, let us know. Thanks ~ Gina T.

  11. I’ve found a 9 year old gelding that I want to buy who is HYPP N/H.. The owner tells me he’s had one attack as a 2 yr old and none since. I’ve done lots of research on this and it looks controllable, but she keeps telling me that he’s “positive” and to make sure I know what I’m getting into. I believe she’s being honest with me about the horse but I wanna make sure there is nothing I’m missing. When someone says he’s HYPP N/H Positive, is that different than just HYPP N/H? Please advise. Thank you..

  12. Hi I have been feeding Timothy and rice bran with psyllium. We live in southern ca where sand is everywhere. I feed her in slow feed bag with 2 flake or whole bale. Which is better in your opinion, a continual feed or flakes twice daily?

    1. Hi Laura, Thanks for the question. We would always advocate for the horse to have ad-lib, or continual, access to hay or pasture. This allows their digestive system to mimic their natural conditions more closely, and can be helpful in preventing things like ulcers.
      Thank you ~ Gina T.

  13. My boy eats triple crown low starch 1.5 q 3 a day and 3 small flakes. He’s had 1 attack 4 years before I got him. I buy Timothy hay from same person

  14. Hi Gina! Do you by chance know how to determine the percentage of potassium there is in a food? As in, how do you know the hay is only 1%? I’m trying to figure out what percentage of potassium I am feeding my horse if I’m feeding my horse 15 lbs of bermuda hay, 1 lb beet pulp and 1 lb oats per day. Is there a calculation somewhere to determine this?

    1. Hello Amanda, You will need to have your hay tested. You can use a service such as Equi-Analytical for this – and it’s the only accurate way to know what is actually in your hay: https://equi-analytical.com/standard-analytical-services/. You can use their “common feed profiles” results area to get some estimates of what might be in your hay or beet pulp or oats, but they are just “estimates” and can vary locally quite a bit: https://equi-analytical.com/interactive-common-feed-profile/. Hope that helps – if you have more questions, please let us know!

  15. Do you have any recommendations for a very hard keeper Senior N/H horse that also has PPID?? He’s only had 4 episodes in 20 years, the most recent during dental work and over sedation by a vet inexperienced with HYPP (but warned 5x by ME!) . Worst experience ever, by the grace of God he was ok with IV’s. So, I’m looking for a feed safe for HYPP and PPID, high enough in fat to keep him thick thru winter (was on LMF but couldn’t hold him over). My vet no longer recommends any sedation/dental care. He’s doing well on pasture but that will change in the next couple months. Please advise!!!

    1. Hi Cassandra,
      Thank you for your interesting question regarding your Senior N/H horse that also has PPID. I am glad to read that he came thru the sedations scare. This combination would generally require a total diet that is below 1.0% potassium and total diet that is below 11-12% non-structural carbohydrate (NSC). Depending on your location, I would recommend a grass hay that is at or below 1% potassium and low NSC, which would eliminate some of the cool season grasses. You should be able to check with your local extension office for recommendations for your area. I would then recommend a low molasses Senior Horse feed to go along with the forage. If you identify your location, we may be able to make a more precise feed product recommendation as potassium content does vary regionally in ingredients.

      Best wishes,
      Roy J.

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