My older male cattle dog has liver disease. As a result of the disease, he had severe gallstones. My vet suggested that Ursodiol had helped a few of her clients, so we decided to give it a try. Within a week, my dog's appetite was better than it had ever been, he regained energy, he got some of his cattle dog sassiness back. He no longer is a gas factory, and he has virtually stopped eating grass and vomiting. A later examination showed that the Ursodiol had dissolved the gallstones.
Please note that once your dog is on it, you will need to keep him/her on it, probably for the rest of the dog's life, as the underlying disease remains. This treats symptoms, it doesn't cure the disease.
If your dog has liver disease and your vet suggests that this might help, it is worth a try. When it works, it works very well. It turned my dog's health around.