Mechanical nociceptive thresholds in endurance horses.

Area of Science:

• Equine sports science
• Veterinary anesthesiology
• Animal welfare science

Background:

• Altering limb sensitivity is prohibited in equine sports but challenging to regulate.
• Objective assessment of mechanical nociceptive threshold (MNT) is needed for endurance horses.

Purpose of the Study:

• To develop and validate an objective field method for assessing MNT in endurance horses.
• To evaluate the practicality, safety, and repeatability of the MNT measurement technique.

Main Methods:

• A remotely controlled pneumatic actuator with a 1 mm tip was employed.
• Mechanical nociceptive threshold (MNT) was measured in the forelimb pastern of 108 endurance horses.

Main Results:

• Median MNT at rest was 1.9 N; icing did not significantly affect sensitivity.
• MNT increased from week 1 to week 3 and significantly increased after racing in horses without impaired sensitivity.
• Desensitized horses showed significantly higher MNT post-racing compared to horses with normal sensitivity; sensitivity returned to baseline within 330 minutes.

Conclusions:

• The MNT measurement technique is practical, non-traumatic, repeatable, and well-tolerated in field conditions.
• This objective method effectively differentiates post-racing MNT in horses with normal versus impaired limb sensitivity.
• The technique supports objective enforcement of regulations concerning limb sensitivity in equine sports.