What is JEB?
JEB is an abbreviation for Junctional Epidermolysis Bullosa which is the new name for the old disease called E.I. (Epitheliogenesis Imperfecto) or hairless foal. This is just a lot of scientific jargon and terms that describe a skin defect that is terminal in certain newborn Belgian foals. This is a simple recessive genetic mutation that occurred many generations back.
How do I identify if a foal has JEB?
This genetic mutation results in the defective production of a skin protein that holds the skin to the body. The foals are typically born alive and well, but soon develop patches of hair and skin loss over points of wear. These patches soon become larger and encompass large areas of the foal’s body. Hoof attachment is also dependent on this protein and with its absence leads to the loss of the hoof wall. The foal dies or is euthanized for severe infection and discomfort at 3 to 8 days of age. The foals also have another important feature and that is the front teeth are in at birth with many oral ulcers also present.
What is the history of JEB?
JEB is not a new problem to Belgian breeders and we have been plagued with this annoyance for centuries. There are scientific reports of this condition dating back to 1934 in Sweden, 1936 in the Netherlands and 28 cases reported in Germany from 1935 to 1944. This condition is not only isolated to the Belgian horse but similar conditions are also reported in the American Saddlebred and even humans. It was through the human research being conducted by the French and the collaboration with Dr. John D. Baird of the University of Guelph, the gene site of the mutation was isolated on January 24, 2002. The isolation of the site removed the largest obstacle in developing a test to identify our carrier and non-carrier horses of the defect.
How does the genetics work with this genetic mutation?
There are three types of genetic animals with this disease:
1) Lethal JEB foals-these horses die shortly after birth and never reproduce.
2) Carrier horses-these horses carry the genetic mutation and it is the breeding of two carrier horses that allows the birth of a JEB foal. Breeding two carrier horses results in the following offspring:
- 25% Non-carrier offspring (N/N)
- 50% Carrier offspring (N/J)
- 25% Lethal JEB foals (J/J)
3) Non-carrier horses-these horses do not carry the genetic mutation and the breeding of two non-carrier horses results in all their offspring being non-carriers. The breeding of a non-carrier to a carrier horse results in the following offspring:
- 50% Non-carrier offspring
- 50% Carrier offspring
The take home message with the genetics of this defect; Do not breed two carrier horses together. By avoiding this combination we will never have another lethal JEB foal again. A successful breeding program can be accomplished by breeding known carriers, as long as they are mated with known non-carriers.
How do I identify which of my horses are carriers and non-carriers?
We no longer have to guess and hope that our breeding program is not breeding two carriers together leading to the production of a lethal JEB foal. The Belgian Corporation has contracted with the Veterinary Genetics Lab at UC Davis to handle the genetic testing for the JEB condition and to handle the testing for our parentage verification. Only registered animals can be tested. The owner of the horse submits the registration papers and appropriate fees to the Belgian Corporation office requesting the JEB test. The Corporate office will then send back to the owner bar-coded paperwork and an envelope. Within this envelope you place the mane or tail hairs of the appropriate horse. These hairs must be pulled and not cut. If the horse is less than 1 year old it is recommended that you pull tail hairs and if greater than 1 year old that you pull mane hairs. Approximately 50 hairs are required for the test.
The roots (bulb) of the hair is what contains the DNA needed for the testing. These hairs can be pulled by the owner of the horse and does not require a veterinarian. The hair samples are very stable and do not require refrigeration or special express mailing. The lab will then do the genetic testing to determine the carrier or non-carrier status and then parentage verification to confirm it was the animal specified. The results will then be returned to the Belgian office and printed on the registration papers as “carrier of JEB” or "non-carrier of JEB”. The registration papers will then be returned to the owner.
Is the Belgian Corporation making this test mandatory?
The test is only mandatory for new breeding stallions. If your stallion has been blood-typed for registration of his offspring his testing is totally voluntary, but if he has not been blood-typed it is mandatory for him to be JEB tested and DNA tested before his offspring can be registered. Blood typing is being replaced by DNA testing. All mares are strictly a voluntary program. All results will be placed on the registration certificates allowing public access to these results.
What does the test cost us?
For years this problem has been a source of rumor and innuendo with breeders as well as cause for concern. We not only financially lose the sale of the lethal foal but also wasted a whole year of the mare’s reproductive life incubating a terminal foal. The test for stallions is $95.00 per animal, the test for mares is $75.00 per animal. For years this problem has been a very sensitive issue with the Belgian Draft horse and has caused many sleepless nights for concerned breeders. We can now rest assured that we have the tools in front of us to manage this condition and move the Belgian breed into the future.