Thyroid problems....

Does anyones dog take Soloxine tablets for an underactive thyroid.

My 10yr old min schnauzer has been on them for about 6 weeks.

His coat has started to flake major dandruff, and i mean major! Its like a snow storm. He is not itchy, just been to groomer today, coat is shiney and hes well in all other ways!

I am waiting for the vet to call back, I am guessing this is a side effect of the tablets as this started about a month into the tablets. He has also just started on Arden grange light, doubt that has anything to do with it, but you never know!

Any suggestions?