Blood in faeces after Metronidazole in dogs

60 reports to the FDA describe blood in faeces in dogs given Metronidazole. That is 1.9% 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.

60Reports

70%Marked serious

8.3%Recovered

38%Died or euthanised

8 daysTypical onset

How soon it started

Same day

7 14%

1–2 days

7 14%

3–7 days

9 18%

1–4 weeks

10 20%

Over a month

16 33%

How the animals did

Recovered

5 8.3%

Still unwell when reported

22 37%

Died

9 15%

Euthanised

14 23%

Not known

10 17%

Problems reported at the same time

38 63%

34 57%

34 57%

30 50%

23 38%

22 37%

17 28%

Didn't work as expected

13 22%

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 blood in faeces in dogs?: 60 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 8 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).

Blood in faeces with similar medicines

Blood in faeces after Amoxicillin + Clavulanate (Clavamox) 29 reports · 0.5% of its reports
Blood in faeces after Doxycycline 23 reports · 0.6% of its reports
Blood in faeces after Cefovecin (Convenia) 22 reports · 0.6% of its reports

All reported side effects of Metronidazole in dogs · Medicines most reported with blood in faeces