10/31/2025
THIS!
🧬 The Importance of Health & Genetic Testing in Breeding Decisions 🧬
At Marlowe Meadows, every breeding decision we make starts with one goal in mind — to produce foals that are not only beautiful, but healthy, sound, and set up for a lifetime of success.
That’s why every mare and stallion we own or breed to is health and color tested.
We believe responsible breeding starts with knowledge — and genetic testing gives us the tools to make the best decisions for our horses and future foals.
Here’s what we test for ⬇️
🔹 HYPP (Hyperkalemic Periodic Paralysis)
• Dominant – only one copy can cause symptoms.
• Causes muscle tremors, weakness, and even paralysis due to abnormal potassium regulation.
• Descends from the stallion Impressive.
🔹 MH (Malignant Hyperthermia)
• Dominant – a horse with one copy can be affected.
• Triggers severe muscle contractions, rapid temperature rise, and potential collapse during stress or anesthesia.
• Dangerous when combined with PSSM1.
🔹 PSSM1 (Polysaccharide Storage Myopathy Type 1)
• Dominant – one copy can cause muscle stiffness, tying-up, and reluctance to move.
• Caused by abnormal glycogen storage in muscle tissue.
• Can be managed with diet and exercise, but should be avoided in breeding when possible.
🔹 MYHM (Myosin Heavy Chain Myopathy)
• Dominant with variable expression – horses with one copy may experience mild to moderate muscle atrophy or stiffness.
• Severe cases can occur with certain stressors (vaccines, illness, or heavy training).
🔹 HERDA (Hereditary Equine Regional Dermal Asthenia)
• Recessive – both parents must carry a copy for an affected foal.
• Affects collagen structure, causing skin to tear or slough off easily.
• No cure — carriers can be safely bred to non-carriers (though we choose not to breed carriers).
🔹 GBED (Glycogen Branching Enzyme Deficiency)
• Recessive – two copies are fatal.
• Affected foals cannot store or use glycogen properly and usually die shortly after birth.
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🎨 Color Panels
We also run color and pattern panels — not just to predict foal color, but to prevent lethal outcomes like LWO (Lethal White Overo).
Breeding two LWO carriers can result in a nonviable foal, and testing ensures that never happens.
Testing gives breeders the power to make the best decisions — ensuring foals are both beautiful and genetically healthy.
🩵 Responsible breeding isn’t just science — it’s respect for the horse.