Tuesday, 17 August 2010 09:19

“Doc – What Is It?”

Written by  A.J. Neumann, D.V.M.
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The purebred Belgian filly “Miracle” at 17 days of age. Note the skinless lesions on her left hock, stifle, hip and elbow. Healing.

I first became a player in this very interesting case involving a newly born Belgian filly via a phone call from its obviously distraught owner on the evening of April 6, 2005. The history obtained over the phone was as follows:

A purebred Belgian filly was delivered on April 1. The birth was normal and both the dam and foal were apparently very healthy with one exception–there were areas of skin missing on the lateral sides of the filly’s hocks, on the point of both elbows, the stifles and in the area over the hip joints. These lesions varied in size; those on the points of the elbows being about as large as a silver dollar, while those on the outside of both hocks were about three or four inches long by one-to-two inches wide. The lesions on the stifles and hip were a bit larger than the lesions on the point of the elbows.

The owner told me he had called his veterinarian to diagnose and treat the condition in the filly. He said his veterinarian had many lab tests performed with no apparent diagnosis of the problem. The owner also stated that his veterinarian had been in consultation with veterinarian researchers in Kansas and Ohio and these people had recommended the filly should be put down as they had made a diagnosis of Hereditary Junctional Mechanobullous from the description of the lesions on the animal. He also mentioned that he had some material describing this condition which he would fax to me early the next morning, April 7.

I asked the gentleman if the stallion, the sire of the filly, had been tested for J.E.B.

He answered, “Yes–he is a non-carrier and it’s recorded on his registration paper.” He added that the mare had not been tested.

“Does the foal have teeth and are the hooves intact?” was my next question. He answered that there was no evidence of erupted teeth and that the filly exhibited no lameness and no separation of the hooves at the hoofheads. In fact, he stated that she nursed well and romped about like any other normal foal would do.

I got his cell phone and house phone numbers and told him I was certain his foal was not a J.E.B. case but to send me the material he had on the diagnosis of Hereditary Junctional Mechanobullous by fax early in the morning. I also requested that the filly should not be put down, as I knew of another condition which I had seen in draft foals whose skin lesions resembled those which are seen in J.E B. cases.

At precisely 7:57 a.m. on April 7, my fax machine started to print out what I needed to know about the diagnosis of Hereditary Junctional Mechanobullous of foals. I’m just an old country practitioner but it didn’t take me long to figure out this was a 1988 term for what we now call Junctional Epidermolysis Bullosa or “J.E.B.” J.E.B. also replaces or is a new name for the old term Epitheliogenesis Imperfecto or E.I.

I phoned the owner of the filly immediately and told him I did not think his filly had J.E.B. or anything like it. I knew what the filly had but could not give a name for the condition because as far as I know there is no medical term for it.

It was just in the “nick of time” as the owner informed me the veterinarian was coming in two hours to put the filly down. We agreed to keep the foal alive as he told me “she appears to be so healthy except for those skin lesions.”

Perhaps some of you may be unfamiliar with the genetic condition called J.E.B. J.E.B. is the abbreviated name for a genetic mutation resulting in a defective production of skin protein that actually holds the skin to body tissue. Usually these affected foals are born alive but soon develop patches of skin loss, especially over points of wear. They also are born with their front teeth in place. If the foal should live for a few days, the hoof wall will become detached and drop off.

This condition has been reported in the Belgian breed, the American Saddlebred and in the human family. Research on the human problem was being done by the French, and, as a result through the collaboration of Dr. John D. Baird of the University of Guelph (Ontario), the gene site of the mutation was discovered in January, 2002. Dr. Baird then developed a test to identify the carrier horses of the Belgian breed.

This test has become very useful to Belgian horse breeders. A J.E.B. foal can only be born if both the sire and dam are carriers of the mutated gene.

In this scenario, the stallion was tested and was a non-carrier, so the foal could not be a J.E.B. case.

I told him over the phone that I would have three J.E.B. tests sent to him as quickly as possible to retest the stallion, the mare and foal. I realized I had to do this in order to prove the filly was not a J.E.B. foal and, after all, there were other parties involved that had apparently diagnosed it as a J.E.B. case. To retest the stallion was very important because it would prove the accuracy of the original test, the result of which was recorded on his registration papers.

I reassured the owner that these tests would be done free of charge. I had made up my mind that testing the three individuals was necessary to prove the accuracy of the test.

I called the office of the Belgian Draft Horse Corporation on Friday, April 8, and was unable to talk to the secretary. So, I asked one of the employees to send three J.E.B. test kits immediately to the foal’s owners, who were members of the Belgian Corporation, free of charge. (I could do this since I am a director of the Belgian Corporation and I thought if the board would not okay the free testing, I would pay for it myself.)

I then informed the owners of the filly that the tests were on the way and reassured them that my diagnosis was correct. The foal's life had been spared and the lesions were being treated with topical applications of wound medicine.

What was my diagnosis? There really is not a name for it. It is a condition which I have often seen in newborn foals especially in the Percheron and Belgian draft breeds. I have seen it occurring occasionally in Clydesdale foals and in several breeds of light horses. I have not seen it in the Shire or Suffolk breeds, as I’ve not had experience with these breeds after foaling.

For many years I have noticed that at birth, some foals will have small areas of skin and hair missing on the “bony ridge” on the outside of each hock. They also may show a loss of hair and skin on the point of the elbow and on the outside or lateral side of the stifle. These lesions are always bilateral (appearing on both sides).

This drawing illustrates as best I can, my theory on how these skinless, hairless lesions can occur. The front leg is positioned over the rear leg which is extended forward. By the position and movement of the front over rear leg pressure can be exerted on the elbow, hock and stifle.

This drawing illustrates as best I can, my theory on how these skinless, hairless lesions can occur. The front leg is positioned over the rear leg which is extended forward. By the position and movement of the front over rear leg pressure can be exerted on the elbow, hock and stifle.

Generally, they are quite small in size. The hock lesions are usually about two or three inches long and a quarter to half-an-inch wide. The elbow lesions are very often no larger than a quarter, while those present on the stifles could be covered with another quarter. Until this case, I have never seen a lesion on the hip area, nor have I seen them as large as they occurred in this filly.
Occasionally I have been at a client’s stable where they have shown me a newborn foal, or one several days of age, and pointed out the hock lesions–”What is this?” On the other hand, many breeders do not notice the lesions and only become aware of them when they are called to their attention by another party.

What is the cause of this condition seen in newborn foals? I really do not know. I have only speculated about it, but I have a theory. Whether it is right or wrong is anyone’s guess. Here is what I think might be a cause of the lesions: A foal lies in the uterus of the mare. Let's suppose the rear legs point toward the foal’s head and the front legs are folded back along the side of the developing fetus in such a way that each foreleg is on the lateral side or outside of the rear limb. As these foals approach maturity in the mare, we know they will move, often violently enough to cause discomfort to the mare. (Water a heavy pregnant mare with cold water and you can often see the movement of the foal in the mare’s abdominal cavity.)

I speculate that the movement of the front hoof on the lateral side of the hock will exert enough friction and pressure on this area to prevent the normal development of skin and hair. Likewise, it is possible that when the developing foal is in this position, the hoof of the rear leg can exert pressure upon the point of the elbow with the same results and appropriate lesions.
It is also possible that the hoof of the front leg could be in contact with the stifle area and cause the same lesion on the lateral aspect of the stifle.

During the past number of years, it has become fashionable to raise “taller” and “taller” draft horses. Years ago, a 16 hh horse was the norm. Now it is quite common to measure draft horses at 18 hh and 18 hh-plus. These horses are equipped with long legs and have become known as the “modern draft horse.” As a result, I believe that this condition of the newborn foal is becoming much more common than in years past.

During the past summer and fall I have made it a point to ask a number of Belgian and Percheron breeders if they could recall seeing these lesions on their newborn foals. Many of them had seen the lesions but almost all of them thought the foal had difficulty getting up and, in the process, caused the hock lesions. Some had seen the areas of skin gone on the points of the elbows. Most everyone who had observed the areas of missing skin were not concerned about it as, generally, these areas were very small. A very few breeders had treated the hock lesions with a topical wound medicine.

I do not think this condition is caused by a dietary insufficiency or is a result of a certain genetic problem. The genetic aspect may be that certain “crosses” could cause their foals to be “long-legged,” thus supporting my theory of the cause.

So what happened to the filly? She was named Miracle and has healed very well without scarring. One of the affected areas on a hock is still a bit thick and not quite healed. I believe this will come down to normal in time, since it is soft to the touch. The Belgian stable had a total of three foals and all three showed tissue loss of some degree or another. The three J.E.B. tests were negative proving all three animals–the mare, foal and stallion–are non-carriers of the disease.

Everyone connected with this case has learned something which perhaps they didn’t know before. First of all, most everyone learned that this condition can occur, especially in draft breeds, and can be, in severe cases, confused with J.E.B. if it occurs in the Belgian breed.

Secondly, a J.E.B. foal can only be born when both the dam and sire are carriers. In this case, the dam was not tested but the sire was tested as a non-carrier. Therefore the foal could not have been a J.E.B. foal and since it appeared healthy, need not to have been destroyed.

Last of all, I learned something. I have never seen a case this bad with such large lesions on the hocks and stifles. I cannot recall ever seeing this condition in a foal with a lesion on the hip.

I would like to commend the local veterinarian who was called to diagnose and treat the foal. He had all sorts of tests, especially blood work, performed. He tried to find something abnormal in the chemistry and health of the filly. He sought professional help from his peers at Kansas and Ohio State, to no avail. Those professional sources had recommended euthanasia of the filly. I believe he tried his very best to diagnose the condition.

Foaling time for another season is upon us and may be here by the time you read this article in The Draft Horse Journal. Check your foals and some of you will see what I have written about and what has been shown to you in the accompanying photos. How ever you may view this condition, the question still remains.” What is it?”

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