September 25, 2026: Is It Really the Hormones?

If you have followed Bee for any length of time, you know we have spent a lot of time working on anxiety. Anxiety under saddle. Anxiety on the ground. Anxiety in new places. Anxiety when separated from friends. Basically, Bee has given me enough material on the subject to qualify for continuing education credits.

But lately, something has changed.

Bee’s anxiety is now pretty darn manageable. Not nonexistent, because she is still Bee, but manageable. Under saddle, I’m getting better at feeling her before she escalates. On the ground, she is much more settled. Between Sarah’s training, everything I’ve learned over the past year, and Bee simply becoming more comfortable with what is expected of her, we have made a lot of progress.

So naturally, once we got one thing working well, I decided it was time to mess with something else.

For quite a while, Bee has been on altrenogest, commonly known by the brand name Regu-Mate. Altrenogest is a synthetic progestin, meaning it acts similarly to progesterone, one of the hormones involved in a mare’s reproductive cycle. It is used to suppress estrus, or what horse people usually call a mare being “in heat.”

Why Put a Mare on Regu-Mate?

Mares normally cycle about every 21 days during breeding season, with estrus generally lasting several days. The obvious signs can include frequent urination, tail raising and squatting, but every mare is different. Hormonal changes can also coincide with behavioral changes that owners notice in training or handling.

For a performance or riding mare, suppressing estrous behavior can sometimes make life more consistent. Altrenogest is used for exactly that purpose. One important distinction is that suppressing the behavior associated with estrus does not necessarily mean completely shutting down everything happening in the ovaries. Follicular development and ovulation may still occur.

In Bee’s case, we were using hormone management as one piece of a much bigger puzzle. When you have a mare who is anxious, reactive and occasionally inclined to make her feelings known in ALL CAPS, eliminating hormonal fluctuations as another variable can be helpful.

And it seemed to help.

But recently, Bee started having opinions about getting her medication. She would move away from me, back up and generally make it clear that she was no longer interested in participating in this particular part of our routine.

And I started wondering: Does she still need it?

So We Tried an Experiment

Unlike medications that need to be gradually tapered, altrenogest does not require a traditional taper before discontinuation. In fact, its reproductive use depends upon mares returning to estrus after the drug is withdrawn. Merck notes that estrus commonly occurs within several days after treatment ends, although individual timing varies.

So about a week ago, we stopped.

And then I basically put the entire barn on Mare Watch 2026.

I told everyone to keep an eye on her. If Bee suddenly became dramatically more “mare-ish,” we would know. I fully expected that within days someone would be reporting that perhaps our little experiment had run its course.

Instead?

Nothing.

She is...Bee.

She still pins her ears occasionally. She still has opinions. She still communicates quite clearly when something does not meet with her approval. In other words, she did not suddenly turn into a gelding.

But she also hasn’t become unusually reactive, anxious or difficult. So far, the horse standing in front of me without hormone suppression looks remarkably similar to the horse who was receiving it.

And that has been really interesting.

Maybe Bee Has Changed. Maybe I Have Too.

It would be easy for me to conclude, “Well, I guess the hormones were never the problem.”

I don't think that's necessarily fair.

Bee today isn't the same horse she was when we started trying to manage all of this. She has had a tremendous amount of training. Her environment is different. Her confidence is better. And the person holding the lead rope and reins has changed quite a bit too.

One of the biggest things Sarah has taught me is to recognize what Bee is telling me before her response becomes big. I’m quieter. I react less. I give her more time to think. I know the difference between Bee being worried and Bee simply having an opinion.

In my opinion, altrenogest helped us during a period when we needed fewer variables while we worked on everything else.

Now the variables are limited and I don’t think we need it.

We're only a week into this experiment, so I am certainly not declaring victory. Hormonal behavior can vary through a mare's cycle, and one quiet week doesn't tell us what the next several weeks will look like. We will keep watching her (and checking for bite and kick marks on the other mare’s in the pasture) and, if her behavior changes significantly, involve her veterinarian in deciding what makes sense next.

For now, though, I am pleasantly surprised.

Bee still has her ears.
Bee still has her opinions.
Bee still has plenty of personality.

Apparently, those weren't prescription dependent.

And truthfully, I wouldn't want them to be.