When thyroid meds have been too high, my heart was racing.
Too low and I feel like I have a fat butterfly in my throat and I am confused and sluggish.
Red was on a high dose (.8) for quite awhile because he was hypothyroid with all the symptoms. He had never been treated by his other family. After he leveled out, we cut it back a little at a time.
You don't say what the levels tested at on the high dosage.
Vinnie had a slight murmur because he did. He lived a long and normal life with his murmur, and only one vet ever heard it out of the four vets he saw.