About This Project

As horse owners, we often use hormones to modify what we consider "poor behavior" in our animals, most commonly with altrenogest (as in Regu-Mate®) or medroxyprogesterone acetate (Depo-Provera®). In humans, it is well known that synthetic progestins suppress the immune system, leading to an increased risk of diseases like HIV and herpes. But do these hormones have similar effects in our horses? We need to find out.

Ask the Scientists

What is the context of this research?

The behavior of horses is often manipulated with hormone therapy; specifically in the administration of synthetic progestins such as altrenogest (as in Regu-Mate®) or medroxyprogesterone acetate (MPA; Depo-Provera®). In humans, it is known that synthetic progestins (like MPA) suppress the immune system, leading to an increased risk of diseases such HIV and the flu. Whether or not these hormones also increase our horses risk of disease has yet to be determined.

Recently, we found that altrenogest changed the immune system of the mare, but we are uncertain as to how it did this, or what effect it may have on the horses ability to fight infection. We need to answer these questions in order to help owners and practitioners make informed decisions for their horses.

What is the significance of this project?

It is believed that 1 in 3 mares will be given a hormone therapy at some point in her life. So in order to improve the overall health of our sport horses, broodmares, and racehorses, it is imperative that we understand the effects of these medications in other parts of the body. Data from our lab indicates that altrenogest does have an affect on the immune system, but we have not studied MPA, or the receptors and pathways through which they both function. Improved knowledge on how they work and the effects that they have will lead to management changes that improve the general health of our horses.

What are the goals of the project?

Our goal is to measure the effects of various progestins on the immune system of horses. All of our horses are located on the University of Kentucky's North Farm and the study will be conducted in the summer of 2018. We plan to get immune cells from at least 10 horses of mixed breed, size, and age. We will isolate the cells from these horses, and assess them for their ability to produce infection-fighting molecules. In addition, we will look at how these progesterone-like drugs activate the cells. Long term, we hope see if these synthetic progestins do increase the risk of various diseases in the horse, including placentitis and leptospirosis, or even how they respond to vaccines.