I've used Raspberry leaf from Herbalcom.com. It's the ingredient in mare magic. It's about $12.00 per lb and the dose we used was a heaping TBSP. Someone else will need to comment on the safety for IR though. This mare was not, but it made a big difference in her comfort. She would rub sores on her hips when in heat. Vets suggestion was Regumate which we did not want to do. This worked for her.
