Chaning cat's thyroid medication.

Dr. Marie replied:

Hi and thanks for your question. It's very unlikely that you have done any harm to Sindibad by altering his medication dose for a few days. In order to see a significant change in thyroid values, he would have to be on a different dose for well over a week. A mild change like this that just lasted a few days really would not have done much. Now, if you had kept him on 2.5mg twice daily for several weeks (when his does was supposed to be 3.75mg in the morning and 2.5 mg at night) then it's possible that he could still be showing some symptoms of hyperthryoidism. But again, just a few days really should not make a difference.

It is also very unlikely that the constipation is due to the dosage change. Having an increased thyroid level (which is what theoretically could happen when medication dose is reduced), if anything, usually causes diarrhea. Now, in very chronic cases, high thyroid levels can lead to kidney problems and kidney problems can lead to dehydration which can in turn lead to constipation. But again, this is not going to happen after just a few days of medication change.

Constipation in an older cat is a very serious matter. If he is still having trouble having a bowel movement then I would have your vet take a look. Sindibad may need to have an enema. Or, the vet may want to be testing him for underlying kidney problems.

I hope things work out ok!

Dr. Marie.

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