Oh my, Quarter horses have a list of diseases that are associated with them. When I did some research for my class, my friend wanted us to cover diseases as well. I found that a lot has to do with their glycogen.
HYPP (Hyperkalemic Period Paralysis)- This inherited disease is characterized by violent muscle twitching and substantial muscle weakness or paralysis among affected horses. HYPP is a dominant genetic disorder; therefore heterozygotes bred to genotypically normal horses have a statistic probability of producing clinically affected offspring 50% of the time.
- Muscle trembling
- Prolapse of the third eyelid - this means that you may note the third eyelid flickering across the eye, or covering more of the eye than normal
- Generalized weakness
- Weakness in the hind end - the horse may look as though it is 'dog-sitting'
- Complete collapse
- Abnormal whinny - this is because the muscles of the voicebox are affected as well as other muscles
- Death - In a severe attack the diaphragm is also paralyzed and the horse can suffocate.
I've seen a horse have to be put down due to this disease.. it isn't pretty, with no cure as of yet.
HERDA (Hereditary Equine Regional Dermal Asthenia)- It develops from a homozygous recessive mutation that weakens collagen fibers that allow the skin of the animal to stay connected to the rest of the animal. Affected horses have extremely fragile skin that tears easily and exhibits impaired healing. In horses with HC, the skin separates between the deep and superficial dermis. There is no cure. Most individuals receive an injury they cannot heal, and are euthanized. Managed breeding strategy is currently the only option for reducing the incidence of the disease. HERDA is characterized by abnormal skin along the back that tears or rips easily and heals into disfiguring scars. The skin is loose, and hyper-elastic in affected horses. Symptoms typically don’t appear until the horse is subjected to pressure or injury on their back, neck or hips, usually around two yrs of age. However foals can show signs when injured, while other horses mature and only show signs in the joints. The expression of HERDA is variable, and the phenotypic range of expression is still being determined.
Also, this disease is traced back to some pretty popular horses. Dry Doc, Doc O'lena, Great Pine, and Zippo Pine Bare.
GBED (Glycogen Branching Enzyme Deficiency)- Recent research suggests that at least 3% of abortions in Quarter horses are due to GBED. Some foals are born alive but are often weak and require warming and assistance to nurse after birth. These foals may appear healthy for a time but eventually the may develop seizures, become too weak to stand, or in some cases, they die suddenly.
- Abortion or still birth of a foal.
- Weakness and low body temperature at birth. Treatment with a bottle, tubing the foal with milk, and assistance to stand and suckle regularly helps the foal become stronger.
- Sudden death on pasture of foals from the heart stopping or from seizures (due to low blood sugar).
- High respiratory rate and weakness of the muscles used to breathe in foals.
- Contracted tendons found in all four legs of a foal.
- Overall weakness and the inability of the foal to get up from lying on its side.
EPSM or PSSM (Equine Polysaccharide Storage Myopathy)- Sub-type of exertional rhabdomyolysis characterized by a defect in glycogen storage in skeletal muscle.
- stiff gait
- muscle cramping
- reluctance to move after exercise.
Truthfully, I think horses should be tested for all of these... Especially HERDA and HYPP. Both make me sick to my stomach...