Part I of this article appeared in the Autumn 2000 issue of the Draft Horse Journal. To fully understand or to help you understand this article, you should read the previous writing if you have not already done so. I wrote in Part I about what can or may happen to the horse who gets too much selenium or Vitamin E in its diet. This paper will deal with the opposite, in other words, too little selenium and Vitamin E in the diet. I will also discuss the role of fat in the ration of the draft horse, as in my clinical experience they all seem to be tied together.

In the horse there are four types of vitamin E and selenium deficiencies that are generally recognized by the tissues that are affected. They are white muscle disease in foals, so-called yellow fat disease of foals, Equine Degenerative Myloen-cephalopathy (EDM) and some reproductive disorders of the mare and stallion.

Vitamin E and selenium deficiencies that are clinically apparent to most practitioners typically involve the newborn foal. These conditions can also be seen in foals up to one year of age. These conditions occur as a result of an inadequate intake of vitamin E and selenium by the mare during pregnancy or during lactation.

As I stated in Part I, the adult horse requires 0.1 mg. per kilogram (0.1 mg/kg) of selenium in dry matter of its forage to meet its selenium requirements. Forage and horse feed locally grown in most areas of the United States and Canada will fall very short of this figure as to selenium content, being often as low as 0.05 mg/kg.

Vitamin E occurs naturally in green forage. When green forage is not available, a Vitamin E deficiency often occurs in the horse unless the vitamin is added to the animal’s ration via the grain or mineral routes.

In the pregnant mare, selenium is transferred across the placenta. This is not the case with Vitamin E. Both E and selenium are secreted into the mare’s milk and colostrum. The mare’s milk and colostrum can be very high in both, providing the mare has had an adequate intake.

We know that the foal needs an adequate supply of E and selenium in order to have a very good immune response to infectious diseases. Vitamin E must come in the colostrum and the first milk for it to be effective to the newborn. Selenium must be there also, except it could come prior to birth to the foal since it can cross the placental barrier.

In the newborn foal with inadequate E and selenium, the immune system would be depressed and that could be an important factor in neonatal diarrhea, pneumonia and naval infections. This condition has been very well documented in calves.

A more severe deficiency of Vitamin E and selenium will result in a foal having considerable muscle damage. Some of these affected foals will be dead at birth, so-called stillborn foals. Others may appear weak, unable to stand, listless and refuse to nurse. Some may appear normal at birth, but as days go by will become weak, listless, stiff, sore and have a difficult time rising. Nursing will be a problem as their tongues do not function properly and appear “stiff.” Along with the stiff tongue they will develop some complications in swallowing.

A number of these young foals will have difficulty in breathing and their heart rate will be fast. Their temperatures will be normal. These foals will be unable to stand or to rise, if down, and will die in a few hours. A post mortem exam of these foals often will reveal extensive heart muscle damage and pulmonary edema.

The affected foals, if left undiagnosed and untreated, will develop swellings on the neck under the mane. These areas will be very painful when palpated. The foals will become emaciated and their tongues will show areas of sloughing.

Blood work should be done on these chronic cases especially since there is time. The CPK and AST tests often will be very high and combined with the symptoms are indicative of an E and selenium deficiency.

Occasionally a foal with hang on as a “poor doer” until it is 4 to 6 months of age. Its hair coat is rough and the animal looks poor. It will invariably have subcutaneous swellings, especially along the ventral abdomen, difficulty in breathing and some fairly hard “lumpy” areas over the body. CPK and AST tests will be elevated.

This picture is typical of the “yellow fat” disease of foals, and often the post mortem examination will diagnose it. This so called “yellow fat” disease will occur in foals, cats, dogs, lambs and calves and is caused by a lack of Vitamin E and not by a deficiency of selenium.

Equine Degenerative Myloencephalopathy (EDM) is a degenerative disease of the spinal cord and brain stem. It can affect horses of any age from one month to twenty years. However it is most commonly seen affecting foals from one to fourteen months of age and becomes very apparent by the time the animal is four years old. The disease is characterized by symmetrical gait abnormalities which may occur very fast or be a long time in developing. To the public this is often referred to as the “wobbler syndrome.” However EDM makes up only about one-third of the “wobbler syndrome” patients.

There are many predisposing causes for the EDM syndrome. Among them are a genetic factor, pyrethrum insecticides, creosote and oil-based wood preservatives and a Vitamin E deficiency.

The role of E is in question. However, some investigators have found Vitamin E levels to be very low at the onset of symptoms of EDM. Others have reported that long-term Vitamin E supplementation was instrumental in the clinical improvements of affected horses.

So even though it appears that EDM may have a genetic predisposition, Vitamin E, when used at 2000 IU/day for prevention and 6000 IU/day for treatment is beneficial to the condition. There is research still to be done on EDM and the role of Vitamin E in its prevention and treatment is yet to be more clearly defined.

The role of selenium and Vitamin E in reproduction problems of the horse is unclear as far as research is concerned. According to the scientific literature available, numerous studies have failed to confirm any benefit of supplementing the diet of the mare or stallion with these products to enhance their reproductive performance.

I disagree with this as a draft horse practitioner. Each year I receive phone calls and letters about reproductive problems of mares and stallions. These inquiries come from breeders of draft horses from all walks of life. In discussing their problems I find that some of these breeders have had their animals on dry forage for at least three or four months. Good green forage is simply not available to their mares or stallions at breeding time.

When discussing their mineral program, I am often stunned by the fact that they are not feeding anything but a simple salt block which was made for cattle use. Some feed salesman has told them that is all they need for the horse! So when does a salt block fulfill the mineral needs of a draft horse, let alone those requirements needed by breeding stock?

Any old time breeder of draft horses knew the best time to service mares was when they were turned out to pasture in April or May. Good green grass contains Vitamin E as well as A, plus selenium if it is available from the soil. Conception rates were better at that time than any other in the Northern Hemisphere. Or course there are other factors to consider in this equation, but back to the original problem—the addition of selenium and Vitamin E to the diet of these mares will often increase their conception rates.

In cattle and sheep lack of selenium in the diet will cause decreased motility of spermatozoa, increased placental retention, increased fetal mortality, slower growth rate of the young and a reduction of milk production. The latter may influence the growth rate of the offspring. Could a lack of selenium in the mare cause the same conditions?

I have not found reports of controlled experiments to determine the efficacy of Vitamin E and selenium to increase libido in stallions. However, in those stallions with decreased libido, who are not overweight or under exercised, I have used alpha tocopherol, which has the properties of Vitamin E, with a good deal of success. Again, this comes from a practitioner’s viewpoint, but for me when a client had the problem the treatment seemed to work in a good many cases.

Many breeders will feed wheat germ oil to their stallions to increase their sexual drive. I believe it is much better to use the alpha tocopherol, as the wheat germ oil will lose much of its Vitamin E content over a relatively short period of time and only the Vitamin B activity will be left in the product.

A serum test can be used on the blood of a horse to determine its selenium status. It is generally agreed that a plasma or serum selenium concentration of 0.1 mg/liter or greater indicates adequate selenium in the diet. A concentration of 0.05 or lower will indicate a selenium deficiency.

There are two ways to provide selenium and Vitamin E in treating a deficiency of these compounds. One is by giving an injection of a product intramuscularly which contains both Vitamin E and selenium. The second method is to feed salt or a mineral mix to horses which contains selenium and Vitamin E. Vitamin E can also be mixed with grain or purchased alone and top dressed over the grain ration.

At present I am using an injectable product which contains 2.5 mg. per cc of selenium and 68 IU of Vitamin E per cc. The dose is 1 cc per 100 pounds given deep into the muscle at the top of the rump. It can be repeated if needed in five to ten days. For years I have advised many of my clients to give an injection of Vitamin E and selenium to their foals as soon as they are born. I believe it seems to give the newly born foal the ability to get up, get going and start nursing.

In cases where just Vitamin E is needed, I use an injectable di-alpha tocopherol product which contains 200 mg. per cc. The dosage to lambs or calves is 1 to 3 ccs. I have given draft foals 20 ccs of this product intramuscularly every three days for a series of four injections upon occasion.

In this country you can buy salt which will contain 90 mg. selenium/kg (90 PPM or 120 mg./kg. (120 PPM). The 90 PPM is generally fed to sheep and 120 PPM is fed to cattle. Either mixture can be fed to horses as the only salt available. Consumption of one-half ounce of this salt per day by the horse would provide it with an adequate amount of selenium. The concentration of selenium in this salt is so little that the horse would have to eat a pound of it a day in order to produce selenium toxicosis, but it is extremely unlikely a horse would do so.

A number of feed companies have been licensed to add selenium and Vitamin E to their mineral mixtures. Feeding these according to the company’s directions should provide adequate selenium in the diet of the draft animals. In any event, take care that the diet does not contain more than 2 to 5 mg./kg. of selenium because this amount will become toxic to the horse.

Now let’s turn our attention to fat in the diet of the horse. It wasn’t so long ago that the thought was for the horse to have a high protein diet to maximize its athletic performance. After many studies performed on the subject, it has been determined that the equine athlete’s total diet dry matter be between 10% and 16 % protein. It is now generally thought the total protein of the ration for an adult draft horse should be about 12%.

It has been found that a high fat diet will have some direct benefits for the working (or you may say the athletic) draft horse. Added fat to the diet will aid the working draft animal by allowing the horse to take on more dietary energy without greatly increasing the volume of feed required. Fat added to the diet will increase the muscle glycogen utilization which in aerobic activity will help to delay fatigue. Also a high fat diet has shown to increase the muscle glycogen content especially if fed over a period of eleven or twelve weeks. Last of all, and this may be of real value for the working draft horse, fat decreases the heat load and therefore increases the amount of energy left over for physical work. The gist of all of this is that a high fat diet will delay fatigue and improve the performance of the horse at low or high work levels.

One study was of interest to me especially at this time of year with the Iowa winter approaching. This study concluded that when fat was added to a horse’s diet the total heat production was reduced by 14% and had no effect on the total energy available. I would conclude from this that a drafter on a high fat diet would have lower heat production and therefore should be stabled or blanketed in cold weather. You certainly would not turn him out into a wind chill factor of 40 or 50 below zero.

High fat diets can be fat added up to 10 to 15% of the total diet. The products used vary from animal fat through the various grain and vegetable oils such as soy, corn or canola oil.

A hidden feature of adding fat to the diet is what it does to the hair coat of the animal. It has been known by horsemen for ages that several ounces of any of the above oils added to a horse’s ration daily would make his hair coat slick and shiny.

Adding fat to the ration of a draft horse will lower the amount of grain to be fed to produce the same amount of energy for the work to be performed. This in fact will reduce the chance of founder and in some cases colic. However, I believe this to be of more value in the light horse industry than in the draft.

There is yet another use for fat added to the diet of horses. High fat, high protein and low carbohydrate diets have been used in horses suffering from equine polysaccharide myopathy (EPSM).

So what is EPSM? It is a condition where the horse will show exercise intolerance and/or various forms of lameness in varying degrees. Usually these animals will have a history of numerous attacks or will exhibit some form of chronic lameness or a peculiar gait. They often will be reluctant to back and may have difficulty in getting on their feet. Some of these horses will appear normal and just collapse and go down. Many of the affected animals will show a lack of muscle mass and a lack of energy with a reluctant poor performance. The diagnosis is made by histopathologic examination of muscle tissue taken from the live or dead animal in the semitendinosus muscle region.

EPSM has been found to occur in many of our horse breeds. They are the Quarter Horse, Morgan, Arabian, Welsh-cross ponies, Standardbred related horses, Belgian, Percheron, Clydesdale, Shire, draft mule, Norwegian Fjord, Haflinger, crossbred draft, and draft/light horse crosses. The condition is possibly more severe in the draft breeds. Age can vary from one to twenty years. EPSM is a metabolic disorder in which up to 40% of type II muscle fibers of the animal may be involved.

Dr. Beth A. Valentine, in conjunction with other scholars, has done much to identify this condition in the draft and draft cross animals. Her work has been reported and printed in many of our veterinary medical journals as well as being published in various horse related periodicals. One can find her reports and read them and greatly enhance your knowledge of the condition EPSM. From time to time she has sent the reports to me on her work in this field and I greatly appreciate the work she has undertaken and the discoveries she has made regarding this form of myopathy.

As a practitioner I find there still is much to be learned or understood about this condition, especially as it involves the draft horse breeds and the draft cross horses. An example: I was called to visit a barn where a group of mares were being held to collect urine. It was a new facility and everything was operating under the newest and best procedures. There were about seventy to eighty mares in the herd. Mares were dying. I was called in as the fourth veterinarian. The two local veterinarians were on the case as well as the State College of Veterinary Medicine.

The mares were from different owners and were mostly of the Belgian and Percheron breeds. They had lost four mares when I arrived and a fifth one was down and still alive at one of the veterinarian’s hospital.

The afflicted mare would begin to sweat and then lie down. As the condition progressed, she would get up and be very uneasy. She would tremble, usually starting with the muscles of the rear quarter. Then the rear quarters would become weak and the animal would go down. It was always the rear quarters and legs which went first. After the mare was down she would still eat and drink for a day or two and then die. It was the Belgians who had died, although several Percherons had shown the symptoms but had not worsened. There were several Belgians and a Percheron showing the symptoms on my first visit to the farm. This was a mixed group of mares from several owners and animals from different owners were being affected. A diagnosis of botulism had been made and the mares had all been vaccinated but new cases were appearing.

The animals were being fed a good grass hay which came from Kansas, a grain ration, which by the way had been changed, and good clean water. They were let out into a large yard to exercise. They were receiving no mineral supplement and no selenium or Vitamin E except which might be in the hay or grain.

I tentatively diagnosed the problem as some form of equine myopathy, possibly EPSM. I recommended the hay be immediately changed, and all of the mares were to receive a dose of injectable selenium and Vitamin E. I instructed them to get salt or mineral containing selenium and E and force feed it to all of the mares. To the down animal at the clinic I gave selenium and E intravenously. The veterinarian there gave selenium and E with fluids via a stomach tube daily. This animal lived about ten days and was then put down. Others so stricken had only lived three to four days. The next day I returned and one of the worst afflicted mares went down in the exercise yard, but we got her up and back into the barn.

The end of the story is that the afflicted mares recovered and there were no more new cases. The exercise yard was reduced in size so the mares could not gallop around in it. To date there have been no more problems of this kind at the farm. It is interesting to note it was the heavier muscled Belgian mares who were affected the most and died. I believe the selenium and Vitamin E played a huge role in treating this condition which appeared to me to be possibly EPSM. No fat was added to the ration for treatment or prevention of this condition.

Several years ago I was teaching a school on the draft horse and mule in Mississippi. There I was contacted by phone by a rather distraught owner of some draft horses from another state. I learned he had a group of draft horses that he was using in the carriage and livery trade. Several of these horses, which he was not using at the time and were in a holding area or corral, had “gone down.” They were placed in slings in a trailer and were taken to the State Veterinary College where they were diagnosed as having EPSM. I then called the clinician at the veterinary hospital who was in charge of the case. Indeed the facts were true. A diagnosis of EPSM had been made by histopathological examination of the appropriate muscle tissue. The live horse at that time was being fed a large amount of fat in the form of an oil.

The horses back at the owner’s paddock were also placed on the high fat diet. The problem, however, was that one more horse in the paddock was showing symptoms of EPSM, and the distraught owner was getting it ready for shipment to the clinic. I tried by telephone to get the clinician to put the horses on a selenium/Vitamin E treatment. I was not successful.

I contacted the local veterinarian and found out there were several horses in the group which were showing the symptoms plus the one going to the college clinic. Through him I got the horses on a selenium and Vitamin E salt which was force fed. The afflicted ones were treated with the selenium and E injections. All recovered except the ones sent to the college. With the addition of a balanced mineral and Vitamin E to the ration no more cases of this kind have appeared in the horse herd.

This case was interesting because the horses were not receiving any mineral–only a salt block. They were receiving good grass hay and were being fed a grain mixture. The horses were well cared for and as the horseman would say, “in good shape.”

There is some speculation that a “shiverer” and a “stringhalt” horse are the products of EPSM. For the last four years I have treated every one of them that I could by placing them on a high fat diet, low in carbohydrates and with adequate Vitamin E and selenium available in the ration. I’ve practically floated some of them off with oil. I have had no results in improving their condition. In fact, they were all sold or destroyed or in the case of several stringhalts, were operated.

I could go on listing case reports about animals who were treated for various forms of myopathy, but that is not the purpose of this article. I know that EPSM occurs and I know the draft animal can be screened for it. But I do believe from my own personal experience as a practitioner that a selenium and/or Vitamin E deficiency has something to do with its onset.

I have found that a high AST (SGOT) test, >300, indicates to me the animal is deficient in selenium. I have tested horses who had a high >300 AST test who appeared normal in every other respect and brought this figure down to normal (100 to 300) by the addition of selenium and Vitamin E to their diets within a time frame of eight to sixteen weeks. There was no fat added to the ration to accomplish this.

So there you have selenium and Vitamin E in a nutshell. I told you when I started this it would be written through the eyes of a veterinary practitioner who is not a researcher but a professional person who needs answers when problems arise concerning the welfare of a client’s stock. My advice is to look into the availability of selenium and Vitamin E to your draft horses through the feed that you are providing for them. It may be the most important job you will have this week.