Unresponsive after Levothyroxine in dogs

The FDA has received 22 reports of unresponsive in dogs after Levothyroxine. That is 0.7% 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.

22Reports

91%Marked serious

9.1%Recovered

50%Died or euthanised

–Typical onset

How the animals did

Recovered

1 4.5%

Recovered with lasting effects

1 4.5%

Still unwell when reported

7 32%

Died

5 23%

Euthanised

6 27%

Not known

2 9.1%

Problems reported at the same time

11 50%

11 50%

8 36%

6 27%

Abnormal ultrasound finding

6 27%

Breathing problems

6 27%

Loss of appetite

5 23%

Abnormal radiograph finding

4 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 unresponsive in dogs?: 22 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.
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).

Unresponsive with similar medicines

Unresponsive after Trilostane (Vetoryl) 76 reports · 0.6% of its reports
Unresponsive after Insulin 64 reports · 0.9% of its reports
Unresponsive after Phenylpropanolamine (Proin) 27 reports · 0.7% of its reports

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