Haematuria after Levothyroxine in dogs

The FDA has received 24 reports of haematuria in dogs after Levothyroxine. That is 0.8% 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.

24Reports

67%Marked serious

4.2%Recovered

21%Died or euthanised

24 daysTypical onset

How soon it started

Same day

3 18%

1–2 days

2 12%

3–7 days

0 0.0%

1–4 weeks

5 29%

Over a month

7 41%

How the animals did

Recovered

1 4.2%

Still unwell when reported

13 54%

Died

1 4.2%

Euthanised

4 17%

Not known

5 21%

Problems reported at the same time

Lethargy

10 42%

Liver problems

10 42%

Loss of appetite

8 33%

Urinary tract infection

8 33%

Proteinuria

7 29%

Pyuria

7 29%

Didn't work as expected

6 25%

Excessive urination

6 25%

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 haematuria in dogs?: 24 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 24 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).

Haematuria with similar medicines

Haematuria after Trilostane (Vetoryl) 136 reports · 1.1% of its reports
Haematuria after Insulin 48 reports · 0.7% of its reports
Haematuria after Phenylpropanolamine (Proin) 40 reports · 1.0% of its reports

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