Denamarin - any side effects?

A friend of ours has a non-pug with liver problems. The dog has been on denamarin for a while and has been tolerating it well. Lately, dog has been spitting out the pill, causing them to hide it in food. Dog has also been vomiting intermittantly. They've been to the vet, who ran a number of tests and said the dog has either liver disease or cancer. Since she's 14 years old, the dog isn't a candidate for surgery if it is cancer. The vet has recommended an ultrasound (another $1200) to see if it is cancer or liver disease. My friend feels that if it isn't treatable if it is cancer, and they know the dog has liver problems, why not just treat for liver problems and see what happens? The dog seems happy otherwise, eats normally, just doesn't tolerate the denamarin consistently.

So, the questions I'm throwing out to you all are:
1. any experience with denamarin? How did your dog tolerate it?
2. would you put an elderly dog through the expense and stress of an ultrasound if it was not going to really affect future course of treatment?

I told my friend I'd ask you all, because there's such a wealth of experience here. He wanted me to thank you in advance for any advice or opinions you might have for him. The dog is very loved, and they want to keep her comfortable for as long as they can.
Thanks, guys!

Denamarin is just milk thistle and SAM-E, I believe. I recently started both Bud & Zoe on milk thistle & they've been fine with it. They're both on phenobarbitol for seizures (which has the potential for causing liver damage) and Bud recently had some questionable test results, which is why we started it. Anything's possible, but I don't think that vomitting is a common side effect. An ultrasound shouldn't be too terribly stressful - they don't need to use anesthesia. My vet did several on Pugsy & it was always quick & easy. There's some great information on treating liver disease here: http://www.dogaware.com/health/liver.html#

Linda - I don't have experience with liver problems specifically, but am going through this sort of scenario with Angel.

My thinking is similar to your friend: if surgery/chemo isn't an option they are willing to consider for cancer, then does the expensive test to diagnose cancer really make sense? I say probably not.

That said, I don't know if treatment for liver problems would be more harmful in the absence of the ultrasound.

In my situation, we think cancer is a real possibility, but decided to treat the (obvious) infection and see if that helps with the weight loss. I've decided that due to her age and frailty, neither surgery nor chemo is a desireable path (either might extend her lifespan a bit, but wouldn't necessarily improve quality of life). And surgery is just risky at her age. The infection appears to be on the run, so our next consideration is whether or not to do xrays to look for tumors. I'm leaning towards no...and that's just my own opinion.

Thanks so much for your thoughts and links and experience. I've passed this along to my friend and hope his dog has something that can be managed for a while longer.