🐴 Shivers in Horses: Understanding the Neurological Disorder in 2025 🧠🦵

By Dr Duncan Houston BVSc

When most people hear the term “shivers” in horses, they think of trembling from cold or fear. But in the veterinary world, shivers refers to a neurological condition that affects hind limb control, especially during specific movements like walking backward or lifting the legs. In 2025, though there is still no cure, we know more about managing this disorder to support affected horses and their caregivers. 🧠🐎

🔍 What Is Shivers?

Shivers is a progressive neuromuscular condition primarily affecting the hind limbs. It's often mistaken for behavioral resistance, particularly during farrier work, but it's actually due to dysfunction in the nerves that control limb movement. 🦵

Originally believed to be a type of muscle disorder or a variant of polysaccharide storage myopathy (PSSM), researchers—particularly Dr. Stephanie Valberg—have since shown that shivers is more accurately a nerve-based condition affecting coordination and proprioception. 🧬

🧠 What Happens During a Shivers Episode?

The most recognizable sign of shivers is the exaggerated movement of the hind limbs when a horse is asked to walk backward or have a hind foot lifted. Symptoms include:

• ⚠️ Sudden trembling or spasms in the hind limb
• 🦵 Hyperflexion—lifting the leg abnormally high when backing
• 🔄 Abduction—moving the limb away from the body before slamming it down
• 🛑 Inability to hold a hind leg up for trimming or shoeing

Horses with early or mild shivers often walk, trot, and canter normally going forward, which can delay diagnosis. 🎠

🧪 What Causes Shivers?

The exact cause of shivers is still under investigation, but evidence points to degeneration or dysfunction of Purkinje cells in the cerebellum—a part of the brain that helps coordinate movement. This makes shivers a type of neurodegenerative disorder. 🧠⚡

It is not contagious and may have a genetic predisposition, though breed-related risks are still being studied. 🧬

🐎 Who’s at Risk?

Shivers is most commonly seen in:

• 🎩 Draft breeds (e.g., Percherons, Belgians)
• 🏇 Warmbloods
• 🧬 Occasionally in Thoroughbreds or Quarter Horses

Horses between 5–15 years are often first diagnosed, although it can appear earlier. 📆

🛠️ Diagnostic Tips for Shivers

There’s no single test for shivers, but your vet may observe:

• 📽️ Gait abnormalities when backing or lifting the hind limb
• 📋 A detailed neurological exam
• 📸 Video gait analysis
• 🧬 Rule-outs for other neuromuscular diseases like PSSM

Shivers can mimic behavioral resistance, especially for farriers, but it’s a physical disorder—not a training issue. 🧠🚫

⚠️ Shivers vs. PSSM

While they can overlap, shivers and PSSM are distinct:

• 🧬 PSSM is a muscle metabolism disorder
• 🧠 Shivers is a neurological coordination disorder

Some horses may have both, which complicates management. Blood tests and muscle biopsies can help differentiate. 🔬

🚫 Is There a Cure?

Unfortunately, there is no cure for shivers. Symptoms may improve with rest, but they usually recur once exercise resumes. Over time, signs may worsen. 😞

💡 Management Strategies for 2025

While there's no cure, you can manage symptoms and support quality of life:

✅ Nutritional Support

• 🍽️ Diet low in non-structural carbohydrates (NSCs)
• 🧈 Higher fat content to provide alternative energy sources
• 💊 Vitamin E supplementation to support nerve and muscle health

✅ Exercise Adjustments

• 🚶 Light, consistent work to maintain mobility
• 🧘 Avoid backing or tight turns that trigger symptoms
• 🛌 Allow rest days if symptoms flare

✅ Farrier Care

• 👟 Work with a patient, experienced farrier
• 🔄 Consider stocks or sedation for safety during hind limb trimming
• 🪑 Provide a supportive surface to reduce discomfort

📲 Ask A Vet for Custom Shivers Plans

If your horse has trouble backing, slams the hind foot down, or gives the farrier a hard time only in the rear, shivers could be the cause. Visit AskAVet.com or use the Ask A Vet App for expert evaluation and management plans. 📱🧠

Dr Duncan Houston and the team can guide you through nutritional adjustments, supplement protocols, and behavioral evaluations to support horses with neurological disorders like shivers. 🐴💬

🏁 Final Thoughts

Shivers is a chronic neurological disorder, but it doesn't mean the end of your horse's career or comfort. In 2025, with the right management—including diet, gentle exercise, and knowledgeable farrier care—many horses with shivers can maintain a good quality of life for years. ❤️

If your horse shows hind limb tremors, resistance to trimming, or unusual movements when backing, don't ignore it. Investigate early, and manage with care. 🧠🐎

Need a customized care plan for shivers? Visit AskAVet.com for real-time veterinary guidance 🐴🧠