Ask Horse Journal: 02/02

Vitamin E Implicated In Neurological Problem
y Morgan was diagnosed with a wobbles-like problem called neuraxonal dystrophy. I’m told it’s because the hay in our area is low in vitamin E. Can you tell me anything more about it or what I should do’

-Maureen Gray

Neuraxonal dystrophy, or equine degenerative myeloencephalopathy, is a fairly recently described degenerative condition of the spinal cord and brain stem.?? Although vitamin E deficiency hasn’t been proven to be the cause by rigid scientific standards, there’s quite a bit of circumstantial evidence suggesting it is.?? There also appear to be breed links and genetic links within breeds.?? In one interesting study,??nine foals of an affected stallion were studied for a year, along with five other foals from a different stallion, all raised under exactly the same conditions.

The foals of the affected stallion were noted to have one or more periods of neurological abnormality even at this age, although it is often not detected until more advanced, and also had much lower plasma levels of vitamin E than the control foals, despite an identical level in the diet.??

An oral-absorption test showed all foals were absorbing oral vitamin E equally.?? This suggests that vitamin E deficiency per se is probably not the real cause, but rather something about the internal environment of these horses that increases their dietary requirement for vitamin E, or perhaps that they are more sensitive to borderline vitamin E status. There could also be some other dietary factor creating a higher-than-normal demand for antioxidant nutrients, e.g. high iron.??

Remember that “normal” values for vitamins in blood are often only those that must be maintained to prevent overt deficiency symptoms and are probably far different from what optimal levels would be.

Unfortunately, there’s no treatment that will reverse damage that is already present, although supplementation with E and selenium may halt the progression of the degeneration. A minimum of 2000 IU vitamin E per day and 2 mg selenium should probably be used.

It’s important to note here that vitamin E levels are low in all hays, not just in some geographical areas. Loss of fragile antioxidant vitamins, like E and C, is a price we pay when feeding hay instead of live pasture grasses all the time.??

Selenium deficiency is also extremely widespread. Selenium, E and C interact with each other and with other antioxidant systems in the body.?? This is why they’re often recommended to be supplemented together.?? The dosage for vitamin C is a minimum of 7.5 grams/day.


Devil’s Claw And A Set Bow
My mare has a bowed tendon that I believe is set. I have her on devil’s claw to help her out. At this point, I’m not sure she needs it, but she’s been comfortable so I’m hesitant to stop using it. If I decide to show in a USAE show, how long do I need to take her off devil’s claw for it to clear her system’

-Rose Thompson
New Mexico

The major effect of devil’s claw is to control inflammation, a direct pain-relieving action, so if the bow is tight and cool you could see how she does without it.?? You could start it back up again if she needs it. It’s best to check directly with the USAE about withdrawal times, as such rules can change. As a rule of thumb, withdrawal times are usually between two and five days, depending on the individual drug or herb, route of administration and testing methods.


Is moonblindness contagious’ I’ve heard it’s caused by a virus. Does that mean you use antiviral treatments against it or is it a permanent problem for a horse’

-Susan Pen

No, moonblindness is not contagious (doesn’t spread from horse to horse), but it is infectious, caused by an infection.?? We probably haven’t identified all of the organisms that can cause moonblindness but prime offenders are Leptospira and larval forms of the threadworm, Onchocerca, which also causes outbreaks of dermatitis on the midline of the belly.

The eye damage is probably not as much a result of any damage done directly by the infections but rather an autoimmune response, meaning the body’s reaction to the infection also ended up attacking its own tissues in the eye.?? There’s no cure for any damage already done but, if the problematic organism can be identified, you can treat the horse to eliminate that and hopefully arrest the disease.?? Some horses can go for long periods between flare-ups, while others have them with regularity, for reasons that are not entirely clear.??Any flare-ups are best treated with anti-inflammatory drugs like bute or Banamine, and topical steroid ointments in some cases.?? Nutritional support includes MSM and good levels of antioxidant vitamins and minerals.


Biotin Levels
A manufacturer told me that the 50 mg. of biotin per serving being marketed by several other supplement makers is “too much” for the horse to absorb in one day and it’s just money down the drain. My Thoroughbred has typical poor feet and I’ve always felt high levels of biotin, plus a good protein source with methionine and lysine, zinc, vitamin B6, and manganese, was important to hoof health. Does biotin affect the balance of my horse’s overall diet, and is it true more is not necessarily better’

-Barbara Brown

Fifty mg. of biotin might not be too much to absorb, but it could well be true that much of it would be wasted since high levels in the blood are likely to be rapidly excreted in the urine.?? You may see the same thing yourself if you take a high-potency B vitamin and notice that an hour or so afterward your urine is bright yellow (remember, biotin is actually a B vitamin). About 20 mg. a day of biotin seems to be plenty to get maximal benefit in feet where biotin deficiency is actually part of the problem.?? Many people observe that biotin supplementation makes even normal feet grow much faster.??

All the other nutrients you mentioned, as well as essential fatty acids, are indeed important parts of the equation, although manganese deficiency is rare compared to zinc, and many grass hays are actually high in manganese (alfalfa is low) so supplementing manganese without knowing your hay levels could work against you. It can compete with the critical zinc for absorption.??

We can’t say for sure if higher biotin would have any harmful effects, although it’s always a good idea to supplement the Bs as a group unless you know you have a specific deficiency.?? It is true that more is not necessarily better because your horse’s body will automatically get rid of any excess beyond what it needs for normal function.


Mysterious Lameness
My 20-year-old Thoroughbred has had a three-week history of poor coordination in his back end. There’s no known prior trauma or illness. He walks fine in the front, but his back end is tilted — one way at first, but now it’s not consistently one way. He’ll tilt one way or the other. It’s apparently not painful. He stands with his hind legs either wide based or leans for support. He came in one day running from the pasture and he seemed to be able to only have “front brakes,” with his front legs stopping, but his hindquarters seemed to keep on coming.

He’s eating great. He responded well to aspirin for five days, but when that stopped, the problem recurred. We repeated the five-day aspirin therapy and got some improvement in him again.

The vet thinks this is chronic “inflammation of the cauda equinus,” but she said she didn’t need to examine him. My farrier said he can see a small hunter’s bump emerging, but he noted no stiffness, soreness or tenseness when he trimmed him. He agrees that the horse visibly tilts to one side when he walks. He wonders if it’s a subluxation of the sacroiliac due to the ligaments getting old and stretched out. What can I do to help this horse, besides daily aspirin’

-M. Maris
New York

Your horse’s good response to the aspirin is a clear indication that there is an active inflammatory process going on. Unfortunately, it doesn’t help in determining what is causing it or whether it involves the nervous system or the skeletal system.??

Your farrier may be correct that there is an asymmetry to the hindquarters, even a sacroiliac subluxation. The question is whether this is the primary problem or secondary.?? If he does have an acute SI dislocation, palpation around the area of the bump will definitely not be appreciated.?? You would also probably notice pain when the leg is being held up for a trim.?? Pelvic fractures can also cause a twist/shift that creates an asymmetry but again there would be signs of pain.?? The asymmetrical appearance could also be caused by muscle atrophy if the problem is a neurological one.??

Several aspects of your horse’s history suggest a neurological problem, including that the horse doesn’t seem reluctant to move but has a clear problem with controlling his limbs.??Another is the wide-based stance and the tilting.?? Neurological disability makes some horses anxious and reluctant to move.??Others either are unconcerned by it or actually unaware that anything is wrong.

You need an examination by a vet who is familiar with neurological and skeletal problems that can involve the hindquarters.?? If a skeletal problem is suspected, a rectal examination is often helpful in palpating abnormalities in the pelvis, distal spine and hip/SI joints.?? If the horse does seem to be having neurological difficulties, a spinal tap will offer the best chance of an accurate diagnosis.

Problems of this type can be caused by neurotrophic Herpes virus infections, EPM, chronic vitamin E deficiency, or even atypical Lyme’s disease or encephalitis virus infection, such as EEE or West Nile.

Older horses are notorious both for being more susceptible to many infections and for showing atypical manifestations. Until you can get your horse examined, if the anti-inflammatories help him and he doesn’t show signs of intestinal distress from them, check with your vet about continuing this treatment. Anything you can do to limit the inflammatory response will also limit the degree of tissue damage.??

Nutritional support in the form of additional antioxidant vitamins will also help with the inflammatory response.??Vitamin E is especially useful in neurological conditions, dosages of at least 2000 IU/day.?? For best effect, though, it needs the support of other antioxidant nutrients such as selenium, vitamin C and the other trace minerals.


Bermuda Hay
I was happy to see you address minerals needed depending on hay (September 2001), but I was disappointed you didn’t include Coastal Bermuda hay. Do you have any mineral supplement recommendations for those of us feeding alfalfa/coastal hay’??

-Carol?? Adams
New Mexico

We didn’t include Bermuda hay because there’s little information available on mineral levels and because the few analyses we have seen bore little or no resemblance to the average composition figures published by the NRC.????This could be said about any individual hay, of course, but since Bermuda isn’t as widely used as others and studies vary so much and aren’t as well studied, we didn’t feel comfortable making “average” recommendations. Your best bet is to start with a hay analysis.


Get Connected
Trainers are starting to use walkie-talkies instead of shouting to their riders in warm-up rings that are already too crowded and busy. It’s an excellent idea that holds down the noise at a show and allows the trainer to communicate with his rider while standing well outside the ring and without everyone around hearing what he’s telling the rider.

Some riders use headsets or waistpacks, but the most practical alternative seems to be attaching the unit on the belt or boot. We prefer the boot because there’s less risk of bruising if the rider falls; if the walkie-talkie is on the belt, place it in front or on the side but never behind the back because of potential injury to the spine.

Some trainers now use the units when they teach, which saves their voices over a long day. At a show, just remember to remove the unit before going in the ring. While just wearing a walkie-talkie may or may not be against an association’s rules, if it’s turned on (even inadvertently) the rider can be eliminated.


Wheat Bran Fans Take Heart
A common criticism of wheat bran for horses is that it contains a large amount of phytate, a plant substance that can bind major minerals and make them unavailable for absorption, particularly phosphorus. But this theory never made sense to us, since feeding wheat bran without feeding adequate calcium can cause phosphorus toxicity (“big head” disease) in horses, so they must not have much trouble absorbing it.

A study at the Graduate School of Agriculture, Kyoto University, Japan, using both low- and high-phytate diets and studying the degree of phosphorus absorption has confirmed phytate doesn’t interfere in horses. They said: “Phytate phosphorus is considered to be easily absorbed in horses because the major site of phosphorus (absorption) is the lower large intestine where most of phytate is already degraded.”

Most horses thoroughly enjoy a bran mash as much as owners get satisfaction from fixing a “meal” for their charges. Its high phosphorus content makes it a tasty, convenient way to help balance high-calcium rations. Because it can be fed wet, it’s a boon to older horses with chewing problems and horses that may not take in enough water over the winter and are prone to impaction. Mixing half a pound of wheat bran with one pound of alfalfa cubes or pellets, or with two pounds of beet pulp makes a large and satisfying meal with correct balance of major minerals. These feeds are all also good sources of the essential amino acid lysine.