Inappropriate urination after Levothyroxine in dogs

50 reports to the FDA describe inappropriate urination in dogs given Levothyroxine. That is 1.7% of all reports for this medicine, compared with 0.5% across reports for all dog medicines, so it is reported unusually often with this medicine.

50Reports

58%Marked serious

26%Recovered

18%Died or euthanised

26 daysTypical onset

How soon it started

Same day

6 18%

1–2 days

2 5.9%

3–7 days

5 15%

1–4 weeks

5 15%

Over a month

16 47%

How the animals did

Recovered

8 16%

Recovered with lasting effects

5 10%

Still unwell when reported

14 28%

Died

3 6.0%

Euthanised

6 12%

Not known

14 28%

Problems reported at the same time

17 34%

17 34%

12 24%

12 24%

11 22%

Didn't work as expected

11 22%

Liver problems

10 20%

Urinary tract infection

9 18%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Levothyroxine treats an underactive thyroid.

Questions owners ask

Can Levothyroxine cause inappropriate urination in dogs?: 50 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
How soon after a dose was it reported?: In half of the reports with dates, it started within 26 days of the first dose.
What should I do?: Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).

Inappropriate urination with similar medicines

Inappropriate urination after Trilostane (Vetoryl) 405 reports · 3.4% of its reports
Inappropriate urination after Insulin 67 reports · 0.9% of its reports
Inappropriate urination after Phenylpropanolamine (Proin) 40 reports · 1.0% of its reports

All reported side effects of Levothyroxine in dogs · Medicines most reported with inappropriate urination