The key drug used to help horses with equine Cushing’s disease has been linked to a heart valve problem in humans. Could this also be the case for horses?
Researchers with the Free University of Berlin investigated the question in a preliminary study published recently in the Journal of Veterinary Science.
Equine Cushing’s disease, formally known as pituitary pars intermedia dysfunction (PPID), is a common neurodegenerative disease in aged horses leading to reduced dopamine production.
The treatment is based on the administration of the dopamine agonist pergolide, which has been linked to valvular fibrosis in humans.
Professor Heidrun Gehlen and her fellow researchers set out to determine whether pergolide induces valvular disease or affects cardiac function in horses.
Standard tissue Doppler and two-dimensional speckle tracking echocardiography was performed on 23 horses with Cushing’s disease.
Twelve of the horses had been receiving pergolide for the condition and were assigned to the treatment group. The other 11 were assigned to the no-treatment group.
The treatment group had been receiving daily pergolide for an average of 1 year and 7 months, with a range between 14 days and six years.
The study team found that none of the 12 horses under treatment had developed valvular regurgitation. The authors found no differences in the left ventricular systolic or diastolic function of the horses between the two groups.
Follow-up examinations three months later in nine of the treated horses and five from the non-treatment group delivered similar results.
The researchers concluded that treatment with pergolide did not affect the ventricular function nor induce valvular disease in any of the horses receiving the drug in the study.
The authors acknowledged that the treatment period might not have been long enough to show a measurable effect. Studies with longer follow-up periods are needed, they said.
Their results, they added, should be regarded as preliminary.
The study team comprised Gehlen, Judith Fisch, Roswitha Merle and Dagmar Trachsel, all with the Free University of Berlin.
Gehlen H, Fisch J, Merle R, Trachsel DS. Preliminary study on the effects of pergolide on left ventricular function in the horses with pituitary pars intermedia dysfunction. J Vet Sci. 2021 Sep;22(5):e64. https://doi.org/10.4142/jvs.2021.22.e64