…and on the eighth day God created the horse in perfect image to romp, graze, gallop, play, and make manure wherever it darn well pleases, in divine grace.
Junctional epidermolysis bulosa (JET) is an equine inherited disorder, also known as hairless foal syndrome or red foot disease. (1)
JEB is a genetic mutation that prevents protein production that is absolutely necessary for proper skin function, skin adhesion, and strength.
On an affected equine, skin and hooves slough off, leaving open sores. The skin on the body and inside the mouth, and the surface of the tongue, as well as the mucous membranes throughout the body form blisters and lesions all over.
Other symptoms are the outside layers of the hooves falling off, lesions and ulcers in the eye cornea, malformation of the tooth root, incisor teeth present at birth, depression and loss of appetite. (2)
Open sores form within a few days of the foal’s birth and then secondary infections occur.
Newborns die within 3 to 8 days, usually from the secondary infections or from humane euthanasia.
The disease is “Autosomal recessive,” meaning that both parents must carry the recessive gene in order to pass it on to the offspring.
Mutations in the genes COL17A1, LAMB3, and LAMC2 are responsible for proper protein production and functioning. They are necessary for the skin to attach to underlying tissues and layers. (3)
Genes that undergo mutations alter the proteins, causing dysfunctions.
The skin becomes damaged and fragile.
Collagen is also affected, as the gene COL17A1 is responsible for the production of this important element. Mutations cause the protein to be unable to make collagen, and this is what gives structure and strength to the skin. (4)
Foals that are born with JEB appear to be normal at birth.
Since JEB affects mucous membranes, the tongue and gums become blistered, so when the foal attempts to nurse, it is painful. It gives up and just lays there.
Newborn foals must absolutely have the mare’s Colostrum, the milk first produced prior-to and at birth that is rich in antibodies and infection-fighting properties. Colostrum is higher in fat and protein than regular milk, it is high-concentrate nutrients with low volume, perfectly suitable for a newborn’s tiny digestive system.
Foals who do not receive this vital nutrient die from the many bacteria and infections of life in an average barnyard.
A JEB foal cannot nurse because of the blisters, so it doesn’t get the vital Colostrum it needs.
There are tests available to see whether a horse has JEB.
The “Nikolsky Sign” applies pressure to areas of the skin as the skin is observed for slipping in the epidermal and dermal layers. Skin sliding back and forth in opposite directions indicates no adhesion or strength. (5)
Biopsies identify the adhesion quality between the epidermal and dermal area under a microscope.
The “PCR- Polymerase Chain Reaction” test, where hairs are plucked from the mane and tail, with roots intact, are more advanced, and these samples are usually tested for both JEB1 and JEB2. The cost is $35. (6)
There is no cure for JEB.
Breeds documented to have JEB are the American Saddlebred, the American Cream Draft Horse, the Comtois Draft Horse, the Breton Draft Horse, and the Belgian Draft Horse.
Of these, 4% of American Saddlebreds have tested positive, and 12% of Belgian Draft Horses have tested positive for the disease. (7)
This can be prevented with a good breeding program and careful testing.
Horse with these genes should not be bred or placed into breeding programs, but this doesn’t seem to stop some people.
Genetic testing is always highly recommended when purchasing the above mentioned breeds.
Closing as always with the immortal words of Roy Rogers and Dale Evans, “Happy Trails to You.”
1-7: Internet/Wikipedia/Animal Genetics/ Illustrated Guides to Equine Disease.