Walking difficulty after Levothyroxine in dogs

The FDA has received 30 reports of walking difficulty in dogs after Levothyroxine. That is 1.0% of all reports for this medicine, compared with 0.4% across reports for all dog medicines, so it is reported unusually often with this medicine.

30Reports

73%Marked serious

27%Recovered

40%Died or euthanised

28 daysTypical onset

How soon it started

Same day

0 0.0%

1–2 days

4 21%

3–7 days

3 16%

1–4 weeks

3 16%

Over a month

9 47%

How the animals did

Recovered

4 13%

Recovered with lasting effects

4 13%

Still unwell when reported

8 27%

Died

1 3.3%

Euthanised

11 37%

Not known

2 6.7%

Problems reported at the same time

14 47%

13 43%

12 40%

10 33%

9 30%

7 23%

7 23%

6 20%

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 walking difficulty in dogs?: 30 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 28 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).

Walking difficulty with similar medicines

Walking difficulty after Trilostane (Vetoryl) 96 reports · 0.8% of its reports
Walking difficulty after Insulin 32 reports · 0.4% of its reports
Walking difficulty after Phenylpropanolamine (Proin) 29 reports · 0.7% of its reports

All reported side effects of Levothyroxine in dogs · Medicines most reported with walking difficulty