My vet recommended Science Diet for Tressel this afternoon, said he has had the best results with that. Seemed she was having some blockage
and tough time going potty. Anyone use it?

I would look for a better food than Science Diet. Many vets recommend it but it's not good. Look at the ingredients, you want to try and avoid corn, wheat, byproducts and glutens. There are much better foods out there than that one.

Welcome to the board.

What type of "blockage" does Tressel have?

Vets get a percentage of the sales from Science Diet, that's why they recommend it. IMO, SD belongs in file #13.

Ditto. And some of their formulas use ethoxyquin as a preservative (pesticide)

I have to join the ranks of those who Just Say No To Science Diet.

Almost all of their products use little or no meat, use deplorable filler material like peanut hulls, use the aforementioned preservative ethoxyquin, though it is rarely in use anymore, and charge a bundle for the privilege.

It might be worth a conversation with your vet, though. Ask why they are recommending it. Ask them why they think you should change from what you're currently using, and if they know the ingredients of what you're currently using and what ingredients they feel may be causing the problem. Also ask why pet food experts almost universally agree that meat should be the primary ingredient in any pet food, and yet this is rarely the case in Science Diet Foods.

I'd be interested to hear how your vet responds.