Levothyroxine

[Bob431]

My dog has had hypothyroidism for several years and has been on 0.2 mg of Levothyroxine twice daily ever since. Recently, when they did a check on his T4 they found that it was low and they increased it immediately to 0.4 mg.
A week or two later he began to significantly pant and wheeze. Then he decided to give him 150 mg of Theophylline twice daily. Could the thyroid dose change have caused these symptoms or is it a coincidence? Is it normal for a vet to increase a dose of this medication so drastically?  My thoughts were that it should be done incrementally.

[dd2406]

I have a registered Catahoula Cur, and she is 10 years old.  I had to remove her for my breeders because she carried red mange.  Thats okay, because she is" my girl".  I had her spayed after finding out about the red and she has developed hypothyroidism.  She should weigh about 60lbs and she weighs 152lbs.  I am concerned about her health, but my Vet says nothing to worry about and she is on medication for the thyroid problem.  She is my child and I would love any input as to how I shoud handle her health, thanks!!!!!!!

[Bob431]

Thank you for responding. I found out that they do make 0.3 mg Thyro-Tabs. Shortly after these medications were given he was diagnosed by another vet with Heart Disease and Cushing's Disease. I wonder if these medications could have caused or contributed to these problems. The vet specialist said that the doses were high. He put him on 50 mg twice daily, 0.3 mg in the morning and 0.2 mg at night. He said to increase the Levothyroxine very gradually over a period of weeks and not to exceed 0.3 mg. Since the original vet knew he developed heart problems why did he give him these doses. I read that these medications could contribute to metabolic disorders and abnormal heart rhythms. I found out that the original vet has been reprimanded for a variety of things including overdosing. Is giving high doses of these medications negligent given his age and symptoms?

[SwanSong]

That is a huge jump in dose. Essentially, that is going from 200 mcg to 400 mcg. There are no doses between these two but that doesn't mean a vet cannot give smaller two doses together equaling a larger in between amount. It is done in people all the time. Or alternating doses to equal an in between amount.