Hi! This a very difficult question to answer without an ultra sound or X-ray. The foundering, I know sounds strange to you, but if he has a stomach mass, his digestive system will not work right. And this could give the symptoms of foundering. Don't be so hard on you Vet. Let's try to help your horse. By doing a rectal he can NOT feel the mass in the stomach area below. All he can do is make sure there is no mass in that area. That would rule out a stone if kidneys or ureter. So we have to do a process of elimination. Now, with this not a possibility, we have to go lower. If your horse has a history of stomach problems, then we have to look at blockage or ulceration that has causes scare tissue or worse. If the mass is near his genitals, than that is a problem. He could have a bowel obstruction or tumorous growth. Just like with people. Animals are just like us. Ideally, because I can not see your horse, you have to be my eyes. If he stretches out to strain to pee he has a problem. If he is kicking or biting at his stomach, that is a problem. Any behavior, that is new is telling you to watch and think. If this is a vital mass, it will continue to grow. If he trying to stand on his toes or heels,. he it telling you his belly hurts. If he is trying to squat, the same thing. Since I am not there, I can only give you a laundry list because I can not see him myself, walk him, touch and make my own decision. You have to help me. Arabs are pretty tough guys, but a stomach mass is critical. You must ask the Vet about an ultrasound to find out where and how big and determine how to treat this. Swelling like he has is not a stone. Please speak to your Vet and ask him what is the next step. If you have any other questions, please ask me. I will do my best to help you!

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