JEB and the American Cream Draft Horse

JEB (junctional epidermolysis bullosa) is inherited as a recessive lethal trait. It is evident within the first few days of life and is always lethal. Breeders and veterinarians who recognize the defect will euthanize the foal immediately.  Several veterinarians and vet schools have made attempts to treat the disorder as they did not recognize it, and always resorted to euthanasia as they were only able to prolong the foals life, but not slow the disease.

Effects of the disease are particularly gruesome, as the foal will eventually shed its hooves and ANY trauma to the skin will result in ever expanding ulcers and breakdown of the skin, resulting in the "sloughing" of the external or epidermal skin layers.  Without euthanasia foals will succumb to infection, dehydration, and shock from the pain of the disease.

Fortunately, these symptoms only affect JEB J/J or "JEB Lethal" horses.  A horse which is JEB N/J is perfectly sound otherwise and there is no reason to avoid such an animal if you are looking to purchase one for pleasure, pasture pet, or commercial/farm work.   JEB N/J only comes into play if you are breeding the horses, which most people do not do. 

Several breeds have genetic defects:  Overo Paints have the "Lethal White", Quarter Horses have "HYPP", Arabs have ASID, and Saddlebreds have another variation of JEB.  

Our strain of JEB seems to have come from cross breeding to the Belgian drafts, as we have the same strain of JEB which is evident in the Belgian breed. Cross breeding to Belgians and other draft breeds done in an attempt to increase the numbers of Creams, only possible because the "Cream genetics" is so dominant.

 Offspring from two N/J parents have a 25% chance of being N/N (no mutation), a 50% chance of being N/J (1 mutated gene), and a 25% chance of being J/J - mutated gene pair - which is 100% lethal. (See table below)

Offspring from 1 N/J (JEB Positive or carrier) to a N/N (normal) are 100% safe from being lethal.  They do, however, have a 50% chance of creating a N/J foal, and 50% chance of an N/N foal.

Offspring from and N/N to N/N breeding will ALWAYS be N/N.

This is the goal of the American Cream Draft Horse Association. To breed out the genetic defect and remove all possibility of future contamination. The only advantage to having such a small gene pool such as ours, is that it is feasible to complete such a task.

How we are going to "breed out" the defect.

Once a horse is tested JEB N/N it "CANNOT" pass on the defect 

because it does not have it to pass on.

This is our goal, to breed JEB N/N colts and fillies from all of the

bloodlines to preserve our breeding base, then curtail breeding 

JEB N/J horses so the defect will be eradicated from our Breed.

The American Cream Draft Horse Association has already begun actions to eliminate this defect from the breed.  

DNA tests are available and required for registration of animals.

Currently, breeders are allowed to breed their own program to save bloodlines with the defect.  No limitations of registrations have yet been enacted.  

The Association sponsored Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Prof. Dr. Phil Sponenberg, Pathology and Genetics and University of Guelph, Clinical Studies, Prof. Dr. John Baird to it's 2004 Annual Association meeting where both presented their views on the disease and steps needed to eradicate it from the breed.

Links to other JEB information sites:

IVIS

FASS TRACK

University of Guelph

Canadian Belgian Horse