Very Common
Less Common
OTHER DIAGNOSES CONSIDERED
Other conditions or ailments that might also need to be ruled out by a vet.
Diagnosis
Conditions or ailments that are the cause of a problem that you see - your observation.
Your vet may diagnose
Glycogen Branching Enzyme Deficiency, GBED
Synonyms: GBED, GBE1 Deficiency, Glycogen Storage Disease Type IV (equine)
Summary
Glycogen Branching Enzyme Deficiency (GBED) is a fatal inherited disease of newborn Quarter Horse and Paint foals (and related stock-type breeds). American Quarter Horse, American Paint Horse, Appaloosa, and other breeds with foundation Quarter Horse bloodlines (the mutation traces to foundation sires such as King P-234 and Zantanon). Not reported in unrelated breeds.
It is caused by a mutation in the GBE1 gene and is passed on in an autosomal recessive pattern — meaning a foal must inherit one copy of the mutation from each parent to be affected. Carrier parents are completely normal and healthy, which is why the disease can appear unexpectedly.
The mutation leaves the foal unable to make glycogen branching enzyme, which the body
needs to store and release sugar (glucose) properly. Without it, abnormal, unusable
polysaccharide builds up and the tissues that depend most on stored sugar — skeletal muscle,
the heart, the brain, and the liver — cannot function.
WHAT YOU WOULD SEE: GBED shows up as late-term abortion or stillbirth, or as a foal that is born weak and never thrives. Affected foals are often unable to stand or nurse, are limp or floppy, run a low body temperature, have low blood sugar, and may have weak or crooked limbs (flexural deformities or contracted tendons). Some have seizures or episodes where they stop breathing, and many die suddenly from heart or respiratory failure.
TREATMENT- There is NO treatment and no cure.
It is caused by a mutation in the GBE1 gene and is passed on in an autosomal recessive pattern — meaning a foal must inherit one copy of the mutation from each parent to be affected. Carrier parents are completely normal and healthy, which is why the disease can appear unexpectedly.
The mutation leaves the foal unable to make glycogen branching enzyme, which the body
needs to store and release sugar (glucose) properly. Without it, abnormal, unusable
polysaccharide builds up and the tissues that depend most on stored sugar — skeletal muscle,
the heart, the brain, and the liver — cannot function.
WHAT YOU WOULD SEE: GBED shows up as late-term abortion or stillbirth, or as a foal that is born weak and never thrives. Affected foals are often unable to stand or nurse, are limp or floppy, run a low body temperature, have low blood sugar, and may have weak or crooked limbs (flexural deformities or contracted tendons). Some have seizures or episodes where they stop breathing, and many die suddenly from heart or respiratory failure.
TREATMENT- There is NO treatment and no cure.
my vet's role
Diagnostics Used
These are tests that might be helpful to make this diagnosis or further characterize the condition.
Very Common
Less Common
Treatments May Include
These treatments might be used to help resolve or improve this condition.
Very Common
PROGNOSIS AND RELEVANT FACTORS
Grave. Foals cannot survive with out this enzyme. Even foals that seem to rally do not survive — essentially all affected foals are aborted, stillborn, or die, or are humanely euthanized within the first weeks of life, most by 8 weeks of age.my role
I might observe
You might make these observations when a horse has this condition.
Skills I Might Need
I might need these skills if my horse has this diagnosis.
Questions To Ask Your Vet:
- ● Could GBED explain my late-term abortion, stillbirth, or weak foal that died?
● Should we DNA test this foal (or tissue from it) to confirm GBED?
● Are my mare and stallion carriers?- How do I get them tested?
● If both my breeding horses are carriers, what are the odds of an affected foal?
● How do I keep using a valuable carrier horse in my breeding program safely?
Prevention
The value of recognizing GBED is twofold: it explains otherwise mysterious abortions, stillbirths, and weak-foal deaths in stock-horse breeding programs, and — most importantly — it is completely preventable through DNA testing of breeding stock.
further reading & resources
Outside Resources
CREDIBLE EQUINE HEALTH INFORMATION ON THE INTERNET
