Advice on supplements for thyroid issues

So my two year old male guinea pig got diagnosed with an inoperable thyroid tumor today. About the size of a dime. He is not showing any symptoms of anything. He’s maintaining weight at about 1150 grams. He eats, drinks, poops all normally. My vet doesn’t want to put him on thyroid meds yes because of this. So I’m looking into thyroid supplements. I only found one thyroid supplement for Guinea pigs. Amber Naturalz TYD. However my concern with this supplement is that it’s got alcohol in it. Would the alcohol negate any of the potential advantages of the supplement? Any other suggestions welcome.