ACTH is useful for the diagnosis of PPID but has important limitations. The association between clinical signs and ACTH is relatively poor and ACTH alone is not a good indicator of laminitis risk. The concept of equivocal zones is useful because PPID has no clear cut clinical or histological start point. The pars intermedia produces a plethora of hormones and a single 'cut off' for ACTH is unrealistic. Assessment of equivocal cases must particularly focus on signalment and the full clinical picture but clearer results may be obtained by an assessment during a period of natural stimulation (autumn) or following artificial stimulation of the pars intermedia with TRH.
Edward Knowles, MA VetMB MVetMed DipECEIM MRCVS
Head of Hospital at Bell Equine Veterinary Clinic
RVC Equine Theatre 1
Friday, November 15 at 11:40 AM