Understanding the Pain Cycle in Horses - Part 2: When the Nervous System Becomes the Problem

If peripheral sensitization continues unchecked, changes can begin to occur higher up in the nervous system. The spinal cord and brain may start amplifying pain signals—a process called central sensitization.

At this stage, pain is no longer tightly linked to tissue damage. The nervous system itself has become hypersensitive.

When the nervous system becomes sensitized, even light touch can feel uncomfortable—an outward sign of nerve-driven pain rather than a new tissue injury.

Central Sensitization: When Pain Spreads

With central sensitization:

• Pain responses become exaggerated

• Discomfort may spread beyond the original injury

• Gentle touch or light movement can provoke strong reactions

The body has, in effect, “learned pain.”

Neuropathic Pain in Horses

In some cases, pain becomes neuropathic, meaning the nerves or their control centers misfire even without active tissue injury. This type of pain does not always correlate with imaging findings or traditional lameness exams.

Common signs include:

• Overreaction to light touch, brushing, or tack

• Inconsistent or asymmetrical movement

• Widespread sensitivity along the neck, back, or hindquarters

• Emotional or stress-related escalation of pain

• “Behavioral” issues despite normal diagnostic results

When reactions are large but the identifiable lesion is small—or absent—nerve-driven pain should be considered.

The Key Takeaway

Pain is not just a structural issue. It is a sensory and emotional experience shaped by the nervous system. Treating the system, not just the sore spot, is often essential for meaningful improvement.