Heart murmur after Metronidazole in dogs

The FDA has received 40 reports of heart murmur in dogs after Metronidazole. That is 1.3% 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.

40Reports

90%Marked serious

10%Recovered

28%Died or euthanised

16 daysTypical onset

How soon it started

Same day

5 21%

1–2 days

4 17%

3–7 days

1 4.2%

1–4 weeks

5 21%

Over a month

9 38%

How the animals did

Recovered

4 10%

Still unwell when reported

19 48%

Died

4 10%

Euthanised

7 18%

Not known

6 15%

Problems reported at the same time

26 65%

21 53%

21 53%

20 50%

16 40%

16 40%

16 40%

15 38%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Metronidazole treats some bacterial and parasitic gut infections.

Questions owners ask

Can Metronidazole cause heart murmur in dogs?: 40 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 16 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).

Heart murmur with similar medicines

Heart murmur after Amoxicillin + Clavulanate (Clavamox) 48 reports · 0.9% of its reports
Heart murmur after Doxycycline 35 reports · 0.9% of its reports
Heart murmur after Cefovecin (Convenia) 21 reports · 0.6% of its reports
Heart murmur after Enrofloxacin (Baytril) 31 reports · 0.8% of its reports

All reported side effects of Metronidazole in dogs · Medicines most reported with heart murmur