A First Step?

If you choose to try heat regulation, choose daily oral altrenogest for the first month of treatment (one example, above). Altrenogest is the only reliable, FDA-approved method of estrus suppression currently available. If your mare doesn’t improve on oral altrenogest, she’s not likely to respond to other methods of control. But if she does, then that's a reliable indicator her behavior problems are heat-cycle related. Then you can continue with altrenogest—or explore other options.