Diagnosis of equine pituitary pars intermedia dysfunction

The key to accurate test evaluation is that reference values reflect both the time of the year and the breed of the horse.
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Diagnosis of equine pituitary pars intermedia dysfunction
Vet J. 2023 Oct 5:106036. doi: 10.1016/j.tvjl.2023.106036. Online ahead of print.
Authors
Allison J Stewart 1 , Joanne L Ireland 2 , Andy E Durham 3 , Catherine M McGowan 4
Affiliations

1 The University of Queensland, Gatton, QLD, 4343 Australia.
2 School of Veterinary Science, Faculty of Health and Life Sciences, The University of Liverpool, Neston, CH64 7TE, UK.
3 Liphook Equine Hospital, Liphook, Hampshire, GU30 7JG, UK.
4 School of Veterinary Science, Faculty of Health and Life Sciences, The University of Liverpool, Neston, CH64 7TE, UK. Electronic address: cmcgowan@liverpool.ac.uk.

PMID: 37805159
DOI: 10.1016/j.tvjl.2023.106036

Abstract

Equine pituitary pars intermedia dysfunction (PPID) is common in aged horses. The majority of horses respond well to treatment, but treatment is lifelong, meaning accurate diagnosis of PPID is important. Similar to any condition, there is no perfect laboratory test to diagnose PPID and accuracy is affected by the characteristics of the population in which the test is being evaluated. This review details the importance of consideration of clinical factors and diagnostic test accuracy. Basal adrenocorticotrophic hormone (ACTH) concentration is used most frequently in practice and has very good diagnostic accuracy when used in combination with clinical judgement and the correct application of diagnostic thresholds. The thyrotropin-releasing hormone stimulation test can be used in horses with equivocal test results following basal ACTH testing, or to evaluate subtle cases due to its improved accuracy.

Keywords: ACTH; Laboratory test; PPID; Sensitivity; TRH.