It's very much a matter of Prasend being far more expensive than compounded pergolide at doses greater than 1 mg daily. Both are effective at the right dose, but if one cannot afford the right dose, PPID will not be controlled.
When my mare got up to 3 mg daily, I stopped using Prascend and started using compounded pergolide.
She is currently at 3.5 mg daily (last seasonal high dose was up to 4.5 mg.), and I also have a second mare at 3.5 mg. Both are controlled at this dose, but the cost of Prascend would be about $14/day for both horses. The cost for my two mares is only about $3/day for the 3.5 mg compounded pergolide capsules.
I switched due to the economics, I've found both products to be quite effective. I order 3.5 mg capsules from Thriving Pets Pharmacy, and there are many other compounding pharmacies that are recommended by this group.
It seems some vets are harder to deal with about these issues. I'm grateful mine is paying great attention to how well my mares are doing, and very willing to prescribe what I request.
Best of luck to you and Fargo.
Claudia & Silhouette 2014 California