Measurement of cortisol concentration in the tears of horses and ponies with pituitary pars intermedia dysfunction.

This research article compares tear cortisol concentrations in horses and ponies with Pituitary Pars Intermedia Dysfunction (PPID) versus healthy aged and non-aged horses. The study found that tear cortisol concentrations were significantly higher in horses and ponies with PPID, suggesting that localized cortisol production, or altered cortisol binding, could contribute to this increase. However, there was no significant correlation between tear and serum cortisol concentrations.

Objective

• The researchers aimed to compare the cortisol concentration in the tears of horses and ponies with PPID to that of healthy aged and non-aged horses.
• They also sought to find out if there was any correlation between serum and tear cortisol concentrations.

Animals Involved

• The study involved 11 horses and ponies with PPID.
• As control groups, they also included 20 healthy horses and ponies, 11 of which were non-aged (≤ 15 years old) and 9 aged (≥ 20 years old).
• It’s important to note that all animals in the study were free of any active ocular disease.

Procedure

• Paired tear and serum samples were taken from both PPID and control animals.
• The researchers measured the cortisol concentration in both samples using an ELISA for tear samples and a chemiluminescent assay for the serum ones.
• Different statistical analysis tests were used to compare the groups and to investigate if there was any relation between tear and serum cortisol concentrations.

Results

• The results showed that the median tear cortisol concentration was higher in animals with PPID compared to healthy aged animals, while there was no significant difference in the serum cortisol concentration between the two groups.
• In addition, the median ratio of tear-to-serum cortisol concentration was higher in PPID animals than in the control group.
• Despite these differences, there was no substantial correlation found between serum and tear cortisol concentrations in either the PPID or control animals.

Conclusions and Clinical Relevance

• The study concluded that horses and ponies with PPID had increased tear cortisol concentrations compared to healthy aged animals.
• This suggests possible localized cortisol production in the tear film or changes in cortisol binding dynamics.
• Further research is suggested to explore these potential mechanisms, and to assess if these elevated tear cortisol concentrations have any implication on the delay in corneal wound healing in horses and ponies, both with and without PPID.