🐴 Vet Guide 2025: High Potassium in Horses — Causes, Risks & HYPP Explained ⚠️

By Dr Duncan Houston BVSc

Potassium is a vital electrolyte for every horse. But when levels get too high, serious health issues can arise—from minor muscle twitching to life-threatening cardiac complications. Let's dive into what horse owners should know in 2025. 🧪🐎

⚡ What Does Potassium Do in the Horse's Body?

Potassium helps with:

• 💪 Muscle contraction
• 🧠 Nerve transmission
• ❤️ Maintaining normal heart rhythm

Most of a horse’s potassium lives inside cells. When potassium leaks out or isn’t filtered correctly by the kidneys, it builds up in the bloodstream—a condition called hyperkalemia.

🚨 What Causes High Potassium in Horses?

Several factors can elevate potassium in a horse’s blood:

• ❌ Kidney failure – reduced potassium excretion
• 📉 Cell damage – potassium leaks into bloodstream
• 🍌 Dietary overload – feeding too much potassium-rich feed or forage
• 🧬 Genetic disorders like HYPP

🔬 Clinical Signs of Hyperkalemia

Signs can range from mild to severe and may include:

• 😓 Muscle weakness or trembling
• 😴 Lethargy or depression
• 🐢 Slowed heart rate (bradycardia)
• ⚠️ Collapse or inability to rise
• 🫁 Respiratory distress in severe cases

🧬 Understanding HYPP (Hyperkalemic Periodic Paralysis)

HYPP is a genetic muscle disease found primarily in Quarter Horses. Affected horses experience abnormal potassium movement in and out of cells, triggering symptoms like: 🧬

• ⚡ Muscle twitching
• 🤕 Severe cramps and staggering
• 🚫 Respiratory paralysis (can be fatal)

⚠️ Approximately 4% of Quarter Horses may carry the HYPP gene. Affected horses often show signs before 3 years of age.

🩺 How Is High Potassium Treated?

Veterinary treatment is urgent and typically includes:

• 🩹 IV calcium – protects the heart
• 💉 IV glucose or insulin – shifts potassium back into cells

Monitoring is critical for horses with HYPP or known kidney issues. ⚕️

🥗 Diet Tips to Prevent Potassium Overload

For horses at risk (especially HYPP-positive):

• ❌ Avoid high-potassium feeds (alfalfa, molasses, beet pulp with molasses)
• ✅ Feed low-potassium hay (e.g., timothy, orchard grass)
• 🧪 Test hay for potassium levels if your horse is sensitive
• 💧 Ensure hydration for proper kidney filtration

Note: Pumpkin and certain fruits are high in potassium—always check before feeding! 🎃🍌

📲 Need Help? Ask a Vet!

If your horse is experiencing any of these signs—or you're unsure if their diet is safe—head to AskAVet.com or download the Ask A Vet app 📱 to speak directly with me or another licensed vet. Early detection and smart feeding save lives! 🧠🐴

🧾 Final Thought

Potassium is essential—but too much can be dangerous. Stay proactive, monitor feed sources, and never ignore changes in your horse's behavior or energy. 💡🐎