Koper Equine

Effects on Stress Regulation and Salivary Cortisol in Horses

As equine wellness modalities expand, understanding how different interventions influence stress physiology, nervous system regulation, and behavior is essential. Salivary cortisol is commonly used as a marker of HPA-axis activity, offering insight into physiological stress rather than visible calm alone.

This comparison examines three commonly used modalities—PEMF blankets, Prosix proprioceptive bands, and massage therapy—based on current evidence regarding cortisol, behavior, and neuromuscular regulation.

PEMF Blankets

Recent controlled research (Hartzler et al., 2025) provides a clear evaluation of PEMF blankets and their influence on stress-related outcomes.

What the study demonstrated

The study found that:

• Horses exhibited relaxation behaviors while wearing the blanket, regardless of whether the PEMF unit was activated.

• No additional behavioral benefit was observed when therapeutic PEMF frequencies (1–6 Hz or 10–30 Hz) were used compared to the blanket being worn with the field turned off.

• Salivary cortisol did not decrease under any condition, including both active and inactive PEMF settings.

Interpretation

These findings indicate that:

• The calming effect comes from the blanket itself, not the electromagnetic field.

• The blanket appears to function similarly to a compression or containment layer, producing comfort and relaxation through tactile input and light pressure.

• PEMF activation does not enhance stress reduction or produce a measurable endocrine response.

In other words, the PEMF blanket is effective as a calming tool—but equally effective when it is not turned on, with no demonstrated impact on cortisol or HPA-axis activity.

Prosix Proprioceptive Band System

The Prosix system uses wide elastic bands placed around the chest, barrel, and hindquarters, providing continuous proprioceptive input, gentle compression, and elastic resistance.

What emerging research indicates

Recent findings show that use of the Prosix system is associated with:

• Reductions in salivary cortisol, indicating a physiological shift in stress regulation.

• Improved postural organization, hind-end engagement, and movement stability.

• Increased calm, regulated behaviors and reduced reactivity.

Interpretation

Prosix appears to influence stress physiology by:

• enhancing somatosensory and proprioceptive feedback,

• improving postural stability so the nervous system perceives greater safety,

• reducing inefficient or compensatory movement patterns that contribute to internal stress load.

Its effects are both neurological and mechanical, supporting stress regulation through improved sensory integration and motor control.

Massage Therapy

Massage therapy—particularly slow, parasympathetic-oriented and myofascial approaches—demonstrates consistent effects on both behavior and physiology.

What research consistently shows

Across multiple equine studies, massage is associated with:

• Significant reductions in salivary cortisol,

• Increased parasympathetic activity (slower breathing, softened muscle tone, lowered heart rate),

• Sustained relaxation behaviors beyond the treatment period.

Interpretation

Massage directly modulates the autonomic nervous system and HPA axis through mechanoreceptive and interoceptive pathways, shifting the horse out of a stress state and into a condition that supports recovery, learning, and efficient movement.

Overall Interpretation

Current evidence suggests that how a modality interacts with the nervous system matters more than the modality itself.

• PEMF blankets provide calming effects through tactile and compression-based input, with no added benefit from activating the electromagnetic field and no measurable cortisol reduction.

• Prosix proprioceptive bands demonstrate cortisol-lowering effects by improving sensory integration, posture, and neuromotor organization.

• Massage therapy shows the strongest and most consistent influence on stress physiology, directly lowering cortisol through autonomic regulation.

Together, these findings highlight that interventions engaging touch, compression, proprioception, and fascial sensory pathways produce the most meaningful physiological shifts in equine stress regulation.