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HYPP (Hyperkalemic Periodic Paralysis)


Our American Quarterhorse has HYPP + / -, therefore we monitor her potassium intake. We were wondering if it is safe to use Cocosoya oil as a supplement to her present diet which consists of Oats and Hay. She is also on a diuretic. Prior to our discovery of her being HYPP positive, we did use Cocosoya oil but have eliminated supplements in an attempt to prevent attacks. TC, New York

I have a filly that is 3 years old that I have started riding for about 20-30 minutes a day, not too harsh riding, She is HYPP N/H symptomatic. She has turnout everyday and I exercise her also. My question is she is such a hard keeper I worm her regularly and she gets 2lbs of Equi fuel with 2 scoops of water along with beet pulp and water and she doesn’t seem to be gaining weight. She is on the lean side but not showing her ribs. Since she is HYPP I have her on a strict diet since her potassium can not exceed 2%. Can you recommend something? – SW, California

Dear TC and SW,

HYPP is a complex condition and we could spend a lot of time just going over the basics. So in order to devote more time to specific nutritional and management recommendations for you guys, I recommend that anyone not familiar with HYPP, or, Hyperkalemic Periodic Paralysis, first read my article. At the end of the article, there are specific recommendations from Dr. Sharon Spier, the premier researcher of the disorder:

  • Avoid high potassium feeds like electrolytes and alfalfa hay
  • Use low potassium feeds such as grass pasture and whole grains
  • Feed regular, multiple small meals less than 33g potassium each
  • Feed a diet between 0.6 – 1.5% total potassium concentration
  • Provide exercise and/or turnout
  • Be aware of trigger factors such as fasting or abrupt changes in diet, anesthesia or heavy sedation, trailer rides, stress and others
  • Medicate with diuretics such as Acetazolamide if necessary

Dr. Spier created the following chart that divides common feedstuffs into high, medium and low potassium feeds. If you have a question about a feed that does not appear on this chart, visit and click on “Common Feed Profiles.” There you’ll find exact amounts of potassium in almost every hay, forage and grain available. The comparison charts at make comparing levels of potassium in various supplements easy.

High Potassium Feeds
Electrolyte supplements
Kelp supplements
Alfalfa hay
Canary grass hay
Orchard grass hay
Soybean meal

Medium Potassium Feeds
Fescue hay
Rice bran
Timothy hay
Coastal Bermuda hay
Kentucky bluegrass hay
Oat hay

Low Potassium Feeds
Pure fats and oils
Beet pulp
Corn, oats or barley
Pasture grass
Wheat bran
Soybean hulls

TC, you specifically asked if Cocosoya oil is safe to use in your HYPP mare. According to Dr. Spier, although pure fats and oils fall into the “low potassium feed” category, soybeans and rapeseed (what canola oil is made from) do contain enough potassium to be risky. Therefore, since Cocosoya is made with soybean oil, you may want to turn to another source of fat for energy. We did some homework here at SmartPak and discovered that flax is also relatively high in potassium, so you may also want to avoid supplements that contain flax or are flax-based.

I’d like to make one more recommendation to you, TC. If you are struggling to prevent episodes even while she’s on the diuretic Acetazolamide, you may want to switch from baled hay—which can vary in potassium content with each batch—to chopped, cubed or pelleted hay with a guaranteed analysis. That way, you always know how much potassium your horse is getting.

Another tip for both of you: while electrolytes must be avoided because of their high potassium content, your horse still needs plain, loose salt, and you can easily provide this in SmartPaks during the summer to replace sweat losses and during the winter to stimulate drinking.

Now for the question from SW: how to put weight on her HYPP filly. One trick to encourage horses to eat more and therefore gain weight is to feed them multiple small meals throughout the day. This works especially well for horses with HYPP, because no one meal should exceed 33grams of potassium (the entire diet should contain between 0.6 – 1.5% total potassium). Pasture also works well for horses with HYPP, because its high water content makes it unlikely horses will consume large amounts of potassium in a short time. And pasture is great for putting weight on horses! Fat (or oil) is another excellent method of getting calories into horses, just be sure to avoid soybeans, canola and flax as sources.

I hope these suggestions help. For more information, go to the University of California-Davis website and read articles by Dr. Spier herself.

Lydia F. Gray, DVM, MA SmartPak Staff Veterinarian and Medical Director Dr. Lydia Gray has earned a Bachelor of Science in agriculture, a Doctor of Veterinary Medicine (DVM), and a Master of Arts focusing on interpersonal and organizational communication. After “retiring” from private practice, she put her experience and education to work as the American Association of Equine Practitioner’s first-ever Director of Owner Education. Dr. Gray continues to provide health and nutrition information to horse owners through her position at SmartPak, through publication in more than a dozen general and trade publications, and through presentations around the country. She is the very proud owner of a Trakehner named Newman that she actively competes with in dressage and combined driving. In addition to memberships in the USDF and USEF, Dr. Gray is also a member of the Illinois Dressage and Combined Training Association (IDCTA). She is a USDF “L” Program Graduate and is currently working on her Bronze Medal. Find Dr. Gray on Google+

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