NEW LOW-POTASSIUM FEED FOR CONTROL

OF HYPP

Ginger Rich, PhD*

During the past year, an unprec- edented amount of horse industry and media attention has been placed on the Quarter Horse industry with the con- troversy surrounding hyperkalemic pe- riodic paralysis (HYPP). Stories from The New York Post to Equus have high- lighted the ethical and economic di- lemmas posed by the disease. Recom- mendations on controlling the further spread of the disease range from re- moving positive animals from breed- ing stock to mandatory testing and pub- lic disclosure.

HYPP is a genetically transmitted disease, currently known to be present only in Quarter Horses, Paints, Appal- oosas, Palominos and unregistered horses carrying bloodlines that trace to the AQHA champion Impressive. In total, it 's estimated that more than 100,000 registered horses carry the Impressive bloodline so there's a good chance you will encounter HYPP in the course of your veterinary rounds.

For those unfamiliar with the dis- ease, HYPP is an inherited genetic de- fect transmitted through bloodlines as detailed in a report by Sharon Spier, DVM, Ph.D., at a 1992 meeting of the American Association of Equine Prac- titioners. Characterized by sporadic at- tacks of muscle tremors, weakness, de-

*Director of Nutrition and Research Montana Pride Dillon, Montana

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Horses with HYPP have a defect in the sodium channel, a gateway in the membrane of muscle cells controlling the transfer of sodium particles. With this condition, sodium particles build up inside the cell and potassium builds up in the bloodstream - - hence, the name "hyperkalemia." The abnormal gradient of ions causes muscle fiber depolarization and uncontrollable twitching or muscle failure. Episodes can occur following any stressful event, such as new exercise regimens, trans- port, feed changes, new environment or illness.

Although there is no cure for HYPP, it does not automatically guarantee a "death sentence" for a horse, as has been reported in some media outlets. The disease can be controlled with medication - - and nutraceutical (spe- cially balanced nutritional ration) treat- ment can decrease the frequency and severity of the attacks.

Research shows that HYPP can be managed successfully in most cases with medication, exercise and a low- potassium diet. The best diet for HYPP is to provide a diet containing less than one percent potassium and to feed sev- eral times a day, with free choice of water.

Since the majority of horses afflicted with HYPP can still lead productive lives if their attacks are minimized, Montana Pride, of Dillon, Montana, recently developed a low potassium complete feed which specifically ad- dresses the nutrient requirements of HYPP afflicted horses.

ALFA Care Plus-H provides the low-potassium ration HYPP horses

The Making of ALFA Care P l u s - H

Montana Pride is in the process of developing a full line of nutraceutical feeds. Its first product, ALFA Care Plus - H, has been developed based upon feedback received from a study that was sponsored for the AAEP. Mon- tana Pride added several of its own questions to the survey to obtain sug- gestions for"most wanted" nutraceuti- cal rations. In addition to the HYPP ration, complete feeds for fat horses, thin horses, geriatric animals and foun- dered horses surfaced as the most de- sired.

In early 1993, Montana Pride began development of what is now called ALFA Care Plus-H. While most Mon- tana Pride feeds are made with high- grade, mountain-grown alfalfa - - an excellent source of roughage and crude protein - - the potassium content of an alfalfa-based product was too high for HYPP horses.

As a result, the company began re- searching alternatives and opted for beet pulp. Processors were located to supply beet pulp in the amounts needed - - only to find, after lab testing, that the beet pulp - - usually low in potassium - - was loaded with it[ Further investi- gation found that most processors were automatically adding molasses to make the pulp more palatable, the chief cul- prit in the unexpectedly high potassium content.

Montana Pride negotiated with sev- eral processors, and identified one that would eliminate molasses for our runs of beet pulp. Another source of fiber and roughage products in the new feed

224 JOURNAL OF EQUINE VETERINARY SCIENCE

includes oat trim. Next, corn, barley, soybean meal,

vegetable oil, a small amount of alfalfa to provide an enticing aroma; salt, wa- ter, yeast, a tiny bit of beet molasses for sweetness, anise flavoring and various mineral supplements were added.

It took several months of trial runs at Montana Pride's plant to mix the ingredients in the right ratios to pro- vide the desired nutrient balance and achieve a consistency appropriate for cube form. After each test run, on-site analyses were conducted with the company's Near Infrared (NIR) scan- ners and through an off-site, commer- cial laboratory.

Field Trials

Montana Pride conducted field tri- als with privately owned HYPP-posi- tive horses to determine initial reac- tions. The product was gradually intro- duced into their diets over a period of ten days and test horses readily took to the feed.

Horses reactions to ALFA Care Plus - H mixed with water were also tested. The feed also was readily accepted in this form as well. Horses were moni- tored closely for reactions to the feed. No side effects were reported and bouts of HYPP were kept to a minimum.

University Research

ALFA Care Plus - H also is being researched through the veterinary schools of two universities, including the University of Saskatchewan at Saskatoon and Auburn University, a land-grant university in Alabama. The research projects are in progress and results will be announced by May 1994.

Specifically, the researchers are measuring the effectiveness of ALFA Care Plus - H through serum levels of potassium, potassium challenge tests and weight changes in different ages of horses to determine differing reactions between young and mature horses, as well as the amount of feed needed to maintain body condition at various ages.

The University of Saskatchewan is using a crossover design, in which half of the horses will be randomly assigned to a standard control diet and half to the Montana Pride HYPP test diet. The diets will be fed for an 18-day acclima- tion period and they will then enter a 12-day test period where their suscep- tibility to potassium-induced attacks will be measured. Following comple- tion of this phase, all horses will be switched to the alternate diet and the procedure repeated. Condition of the horse including attitude and overall health, is monitored and irregularities noted.

Clinical exam parameters will in- elude body weight, rectal temperature, food intake and/or refusal and fecal consistency. In addition, serum potas- sium levels will be monitored pre- and post-feeding and an EMG will be per- formed on horses on day 18 on three major muscle groups.

W h a t ' s Next In HYPP?

With more than 100,000 registered horses in the Impressive bloodlines, it is an unfortunate reality that veterinar- ians will have to deal with this disease for years to come. Hopefully, over time, horse associations and breeders will take a definitive position to eradicate and/or minimize the disease to prevent its spread to additional breeds.

In the meantime, horse owners who have invested time, energy and savings into high performance horses diagnosed with this genetic defect can take heart that there are tools and feeds coming onto the market that will help their horses lead healthy, happy, productive lives.

Montana Pride nutraceuticals will not be available through the general public. They will only be available through veterinarians. To obtain more information about ALFA Care Plus - H or to arrange a distributorship, veteri- narians are encouraged to call Montana Pride's special veterinarian hotline at (800) 984-ALFA.For the address of the

Aoout me aumor Dr. Ginger Rich served as a professor

in the Colorado State University Equine Sciences program. She now serves as an independent consultant on equine nutri- tion, and also as the director of nutrition and research for Montana Pride. She has developed the formulas for Montana Pride " s line of premium, life-staged horse feeds in cube form and has begun development of Montana Pride ' s line of nutr aceutical feeds. Dr. Rich is based in Monroe, Connecticut.

MORE INFORMATION ON HYPP DIETS

In the March issue of Equine Vet- erinary Data there is an article on Nutritional management of HYPP. The article describes Low-K, a feed pro- duced by TDI, Inc., Delaware, Ohio, as well as Alfa Care Plus H. The article concludes with the following statement which is appropriate regardless of which low potassium diet is fed: "Because of the great variability in the condition among horses, as well as the influence of environment on frequency and se- verity of the HYPP episodes, a special diet will probably have variable effec- tiveness. The low-K diet should not be billed as a cure-all. Of course no guar- antees should be made. It is prudent, however, to put all horses shown to be positive for the condition on the special diet."

Volume 14, Number 4, 1994 225