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I have a Cairn Terrier and he turned 10 on March 25th. My dog weighs 23 pounds. The vet tested him in October and determined that he had an under active thyroid and needed to be put on medication. He has been on the medicine since then and I took him back to check his thyroid level and now it is high. She wants me to continue the medicine for a month and bring him back for another test to determine if the dosage should be changed. My concern is that he sometimes will act nervous, shakes, and gets hot as long as he is in the house but once he is out he tends to calm down. I am concerned about his reaction at times and the side effects of the medicine. The medication is levothroxin. Please provide me with as much information as possible. Thank you for your assistance.

The dose for levothyroxin has to be tailored for each patient. The conventional starting dose for an animal your dog's size is .2 mg twice daily. It is the case, though, that this dose often must be reduced, sometimes by as much as fifty per cent. It appears that your dog may be showing signs of a mild overdosage and you should ask your vet if there is some compelling reason for not lowering his dose now and rechecking his thyroid levels in a few weeks. The dose can always be increased later if necessary.

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