Evaluation of dynamic testing for pituitary pars intermedia dysfunction diagnosis in donkeys.

This study is an evaluation of current guidelines for diagnosing a common endocrine disorder, Pituitary pars intermedia dysfunction (PPID), observed in horses on a group of donkeys suspected to have this disorder.

Objectives

• The main objective of this research was to validate the application of existing PPID diagnostic protocols for horses on donkeys, considering the common prevalence of endocrine disorders and the possible occurrence of PPID in donkeys due to their longevity.

Methodology

• The research was a prospective experimental study involving 80 donkeys, which were initially examined for PPID based on observable clinical signs and baseline adrenocorticotropic hormone (ACTH) concentrations.
• Out of these, six mixed-breed donkeys, comprising one jack and five non-pregnant jennies, met the inclusion criteria and were subjected to further diagnostic tests including dexamethasone suppression test (DST), thyrotropin-releasing hormone stimulation test (TRH), and a combined DST-TRH challenge.
• To interpret the results of these tests, the researchers followed the guidelines outlined for PPID diagnosis in horses.

Results

• All the donkeys (6 out of 6) who met the inclusion criteria were diagnosed with PPID based on the TRH stimulation test results. However, the DST alone (3 out of 6) and the combined DST-TRH (4 out of 6) tests failed to consistently identify those affected. Also, the cortisol basal concentrations did not align with the suspicion of PPID, demonstrating inconsistent results.

Conclusions

• The study concluded that further detailed investigation is needed to explore the influence of seasonal changes and geographical location on baseline ACTH concentrations and reaction to the TRH in donkeys suspecting PPID.
• Although the research included a limited number of animals and thus only provides preliminary results, these results support the relevance of the current guidelines for PPID diagnosis in horses. The research team recommends measuring baseline ACTH followed by TRH challenge for efficiently diagnosing PPID in donkeys.
• This study’s findings contribute to the body of research as it is the first study focusing on evaluating common dynamic tests used for diagnosing PPID in horses on donkeys.