Long-term treatment of insulin-insensitive mares with cabergoline: Effects on prolactin and melanocyte stimulating hormone responses to sulpiride and on indices of insulin sensitivity

Document Type


Publication Date



The main experiment assessed whether the inhibitory effects of the dopamine agonist, cabergoline, on prolactin and α-melanocyte stimulating hormone (MSH) concentrations would persist throughout a longer-term administration (65days). The possible effect of cabergoline on insulin sensitivity was also studied. Ten mares known to be insulin insensitive were allotted to two groups (treated vs. control). An insulin challenge, a glucose tolerance test, and a sulpiride challenge were administered before treatment. On day 0, treated mares (n = 5) received an injection of 5mg cabergoline in slow-release vehicle; control mares (n = 5) received an equivalent vehicle injection. Injections were repeated every 10days for a total of seven injections. Sulpiride challenges were done 1day before each cabergoline treatment to assess possible refractoriness to the treatment. Behavior and hair coat density were also monitored. Plasma prolactin was suppressed (P < .01) to undetectable levels in mares receiving cabergoline; control mares had robust prolactin responses to each sulpiride injection. There was no indication of refractoriness to cabergoline over time. Plasma MSH concentrations after sulpiride were also suppressed (P < .05) by cabergoline. After treatment, neither the glucose response to insulin nor the insulin response to glucose differed (P > .1) between groups. No behavioral changes were notedbecause of treatment. Weight of hair samples indicated that cabergoline perturbed (P < .05) winter coat growth. It is concluded that 5mg of cabergoline in slow-release vehicle administered every 10days is an effective way of delivering dopaminergic activity to mares that results in no noticeable detrimental effects and no refractoriness to the drug. © 2014 Elsevier Inc.

Publication Source (Journal or Book title)

Journal of Equine Veterinary Science

First Page


Last Page


This document is currently not available here.