Assistant Professor in Equine Internal Medicine VetAgro Sup Marcy l'Etoile, Rhone-Alpes, France
Abstract:
Background: Pituitary pars-intermedia dysfunction (PPID) clinical score (CS) and TRH-Stimulation test (TRH-ST) results may vary according to several factors.
Objectives: To describe the seasonal variations of a CS combined with TRH-ST in aged ponies, and their ability to discriminate between PPIDs and non-PPIDs.
Animals: Nine crossbreed mares aged 15- to 28 years, kept in the same area.
Methods: CS (gradation /33 points scale), and TRH-ST results including basal ACTH concentration ([ACTH]b,), 10 and 30 minutes post-stimulation ([ACTH]10 ; [ACTH]30) were assessed monthly over one year. Results were analyzed using Shapiro-Wilk, Kruskall-Wallis and Spearman tests.
Results: Three mares were PPID, 2 were Controls and 4 were Equivocals. Median CS was statistically higher in PPIDs (18.0 +/-3.6) compared to Equivocals (6.5+/-1.5) and Controls (4 +/-0.5) (p< 0.01). CS results showed intra-individual monthly variations attributed to haircoat changes (n=8), and/or occurrence of several simultaneous infections (n=5), and/or laminitis (n=3), and/or loss of body condition in winter (n=2). May and June allowed optimal detection of hair changes and maximal CS differences between groups. Annual [ACTH]b, and [ACTH] 10,30 were statistically different between the 3 cohorts (p< 0,01). October and November were the most relevant months to differentiate the 3 groups by measuring [ACTH]b, and May for [ACTH]10 - 30.
Conclusions/clinical importance: CS and TRH-ST monthly variations were observed. Groups were best differentiated in May using the combination of CS and TRH-ST. The correlation between TRH-ST and CS results may be variable. Further studies are needed to assess the sensitivity and specificity of the CS.