Reduced-size microchips for identification of horses: response to implantation and readability during a six-month period.
Authors: Wulf M, Aurich C, von Lewinski M, Möstl E, Aurich J E
Journal: The Veterinary record
Summary
# Editorial Summary: Reduced-size Microchips for Equine Identification Researchers implanted 10.9 × 1.6 mm microchips in 40 adult mares' neck tissue to assess whether miniaturisation compromised readability or caused physiological stress compared with standard 11.4 × 2.2 mm chips. When scanned from the chip-bearing side, 100% readability was achieved across all three scanner models at every timepoint over 28 weeks; scanning from the opposite side of the neck yielded variable results depending on scanner type (scanner C maintained 100% detection whilst scanners A and B ranged from 60–100%), though this contralateral scanning scenario is rarely encountered in practice. Crucially, whilst implantation triggered modest elevations in heart rate and heart rate variability (P<0.01), cortisol concentrations remained unchanged, indicating the procedure does not constitute a meaningful stressor for horses. For equine practitioners, these findings support the adoption of smaller microchips without concerns about identification reliability or welfare impacts, potentially offering advantages in terms of reduced implant site reactions and improved animal acceptance.
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Practical Takeaways
- •Reduced-size microchips are reliable for horse identification with consistent readability over 6 months, allowing use of smaller implants without compromising functionality
- •Scanner selection matters for contralateral detection; if reading from the non-implant side is important, use scanner C for guaranteed readability or ensure backup scanners
- •Microchip implantation causes minimal stress response in horses, making it an acceptable procedure with only transient minor increases in heart rate and HRV but no cortisol elevation
Key Findings
- •Reduced-size microchips (10.9×1.6 mm) were readable 100% of the time from the implantation side with all three scanners across all time points (0-28 weeks)
- •From the contralateral side, scanner C achieved 100% readability while scanners A and B ranged between 60-100% across the study period
- •Heart rate and HRV increased slightly (P<0.01) at implantation but cortisol concentration did not increase, indicating microchip implantation is not a pronounced stressor
- •Reduced-size microchips performed comparably to conventional microchips without impairment to readability despite the 4% reduction in length and 27% reduction in width