Chip-based nanoelectrospray ionization with Fourier transform mass spectrometric detection to screen for local anesthetics intended to mask limb sore in walking horses.

The research paper presents a highly efficient method for spotting local anesthetics on horse limbs, which may be used unethically to hide signs of animal abuse. The technique uses nanoelectrospray ionization combined with Fourier transform mass spectrometry.

Technique Employed

• The researchers implemented a high-throughput method that uses a specialized chip for nanoelectrospray ionization. This method is allied with Fourier transform mass spectrometry for detecting local anesthetics in samples acquired through swabbing.
• The technique was specifically refined for lidocaine detection, but was found to be effective in determining sub-ppm (parts per million) mass accuracy for a total of nine local anesthetics that were studied.

Significance of the Research

• The procedure enables faster and more accurate detection and identification of forbidden practices in horse care, such as “soring” — a painful procedure that causes horses to walk with a high-stepping gait that is considered attractive in horse shows, but is highly abusive to the animals.
• Local anesthetics can be used by unscrupulous individuals to camouflage the pain experienced by horses after such abusive practices. The identification of these anesthetics on horse limbs, therefore, serves as evidence of abuse.

Research Findings

• When doped cotton swabs were used, the researchers were able to detect two-third of the analytes after adding 10 ng (nano-grams) of each drug. When the dosage was increased to 100 ng, all of the analytes were detected.
• In swab samples collected during walking horse competitions, the presence of Benzocaine and/or Lidocaine — two commonly used local anesthetics — was identified, confirming the effectiveness and practical applicability of the method.