Proprioception deficit after Levothyroxine in dogs

The FDA has received 30 reports of proprioception deficit in dogs after Levothyroxine. That is 1.0% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

30Reports

90%Marked serious

3.3%Recovered

40%Died or euthanised

28 daysTypical onset

How soon it started

Same day

1 5.6%

1–2 days

2 11%

3–7 days

0 0.0%

1–4 weeks

7 39%

Over a month

8 44%

How the animals did

Recovered with lasting effects

1 3.3%

Still unwell when reported

12 40%

Died

3 10%

Euthanised

9 30%

Not known

5 17%

Problems reported at the same time

14 47%

12 40%

12 40%

8 27%

7 23%

7 23%

6 20%

5 17%

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 proprioception deficit 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).

Proprioception deficit with similar medicines

Proprioception deficit after Trilostane (Vetoryl) 38 reports · 0.3% of its reports
Proprioception deficit after Phenylpropanolamine (Proin) 20 reports · 0.5% of its reports

All reported side effects of Levothyroxine in dogs · Medicines most reported with proprioception deficit