Date Available


Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Agriculture, Food and Environment


Animal and Food Sciences

First Advisor

Dr. Kristine L. Urschel


Equine pituitary pars intermedia dysfunction (PPID) typically occurs in horses older than 15 years of age and is characterized by hair coat abnormalities, muscle atrophy and decreased insulin sensitivity. The first objective of this research was to compare the rate of whole body protein metabolism and relative abundance of key factors in the signaling pathways associated with muscle protein synthesis and protein breakdown in response to feeding in Control and PPID horses. No differences (P > 0.05) were seen between the PPID and Control groups in whole-body protein metabolism or post-prandial activation of the muscle signaling pathways regulating skeletal muscle protein synthesis and breakdown. The second objective of this research was to determine if aged horses with PPID had reduced insulin sensitivity and alterations in the insulin-mediated signaling pathways in the skeletal muscle when compared to non-PPID, aged Control horses. Measures of insulin sensitivity and the activation of factors associated with protein synthesis and breakdown were similar between the PPID and Control groups (P > 0.05). Overall, insulin sensitivity and protein metabolism are similar between the PPID and Control groups. The studies suggest that abnormalities may exist as a function of advanced age rather than PPID status directly.