Colitis after Metronidazole in dogs

The FDA has received 28 reports of colitis in dogs after Metronidazole. That is 0.9% 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.

28Reports

64%Marked serious

32%Recovered

25%Died or euthanised

32 daysTypical onset

How soon it started

Same day

3 13%

1–2 days

2 8.7%

3–7 days

1 4.3%

1–4 weeks

5 22%

Over a month

12 52%

How the animals did

Recovered

8 29%

Recovered with lasting effects

1 3.6%

Still unwell when reported

8 29%

Died

3 11%

Euthanised

4 14%

Not known

4 14%

Problems reported at the same time

17 61%

16 57%

13 46%

12 43%

9 32%

7 25%

Abnormal radiograph finding

6 21%

Blood problems

5 18%

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 colitis in dogs?: 28 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 32 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).

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