Underdose after Metronidazole in dogs

The FDA has received 50 reports of underdose in dogs after Metronidazole. That is 1.6% of all reports for this medicine, compared with 1.0% across reports for all dog medicines, so it is reported unusually often with this medicine.

50Reports

54%Marked serious

38%Recovered

12%Died or euthanised

3 daysTypical onset

How soon it started

Same day

13 35%

1–2 days

5 14%

3–7 days

4 11%

1–4 weeks

4 11%

Over a month

11 30%

How the animals did

Recovered

19 38%

Still unwell when reported

12 24%

Died

4 8.0%

Euthanised

2 4.0%

Not known

13 26%

Problems reported at the same time

14 28%

13 26%

11 22%

10 20%

Didn't work as expected

9 18%

Liver problems

7 14%

Death

6 12%

Wobbliness (ataxia)

6 12%

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 underdose in dogs?: 50 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 3 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).

Underdose with similar medicines

Underdose after Amoxicillin + Clavulanate (Clavamox) 59 reports · 1.1% of its reports
Underdose after Doxycycline 45 reports · 1.1% of its reports
Underdose after Cefovecin (Convenia) 20 reports · 0.5% of its reports
Underdose after Enrofloxacin (Baytril) 38 reports · 1.0% of its reports

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