Low thyroxine (t4) after Leptospirosis Vaccine in dogs

The FDA has received 26 reports of low thyroxine (t4) in dogs after Leptospirosis Vaccine. That is 0.3% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported unusually often with this medicine.

26Reports

88%Marked serious

0.0%Recovered

42%Died or euthanised

4 daysTypical onset

How soon it started

Same day

6 32%

1–2 days

3 16%

3–7 days

2 11%

1–4 weeks

5 26%

Over a month

3 16%

How the animals did

Still unwell when reported

8 31%

Died

3 12%

Euthanised

8 31%

Not known

7 27%

Problems reported at the same time

17 65%

17 65%

17 65%

14 54%

13 50%

11 42%

10 38%

Abnormal ultrasound finding

10 38%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Type: vaccine.

Mild, short-lived lethargy, soreness or a small lump at the injection site are the most commonly reported vaccine reactions.

Questions owners ask

Can Leptospirosis Vaccine cause low thyroxine (t4) in dogs?: 26 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 4 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).

Low thyroxine (t4) with similar medicines

Low thyroxine (t4) after Rabies Vaccine 22 reports · 0.2% of its reports
Low thyroxine (t4) after Bordetella Vaccine 22 reports · 0.2% of its reports

All reported side effects of Leptospirosis Vaccine in dogs · Medicines most reported with low thyroxine (t4)