Measurement of phenol red thread tear test in Arabian and throughbred horses.

This study examines the tear production levels in Arabian and thoroughbred horses using a method called the phenol red thread test.

Research Purpose

• The intention of this research was to identify the physiological levels of tear production in both Arabian (AH) and thoroughbred horses (TH) utilizing the phenol red thread test (PRT).
• The PRT is a diagnostic tool used widely in human ophthalmology to assess tear production, and its application in veterinary medicine is an emerging area of exploration. The researchers want to establish its reliability and effectiveness when used with horses.

Methodology

• The research was undertaken on a group of 16 AH and 14 TH, each ranging from 2.5 to 24 years of age and housed in a stable located in Sanliurfa, Turkey.
• The PRT involves placing a strip under the horse’s lower eyelid approximately one-third the distance from the temporal to the nasal canthus (the corner of the eye) and leaving it there for 15 seconds.
• After removing the strip, the researchers measured the length of the wet area on the thread, recording the results in millimeters.

Results

• The average length of the wet area measured significantly similar for both AH (30.22 +/- 0.99 mm, range 16-41) and TH (31.00 +/- 1.4 mm, range 14-47).
• There was no notable difference in results when comparing breed, sex, or age groups, indicating that these factors do not significantly affect tear production in horses.
• Interestingly, the measurements taken from the left eyes were consistently higher than those from the right eyes, a phenomenon observed across both horse breeds.

Conclusion

• The researchers concluded that the PRT is both an efficient and non-invasive procedure for measuring tear production in horses.
• Given its simplicity and the lack of associated discomfort, they suggest its routine application in equine ophthalmology.
• Furthermore, these baseline PRT values could be helpful in diagnosing keratoconjunctivitis sicca (a condition of insufficient tear production causing dry eye) in horses.