Splenomegaly after Metronidazole in dogs

29 reports to the FDA describe splenomegaly in dogs given 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.

29Reports

93%Marked serious

3.4%Recovered

45%Died or euthanised

22 daysTypical onset

How soon it started

Same day

3 13%

1–2 days

2 8.7%

3–7 days

3 13%

1–4 weeks

6 26%

Over a month

9 39%

How the animals did

Recovered

1 3.4%

Still unwell when reported

9 31%

Died

4 14%

Euthanised

9 31%

Not known

6 21%

Problems reported at the same time

20 69%

19 66%

18 62%

16 55%

14 48%

13 45%

12 41%

Abnormal ultrasound finding

11 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 splenomegaly in dogs?: 29 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 22 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).

Splenomegaly with similar medicines

Splenomegaly after Amoxicillin + Clavulanate (Clavamox) 32 reports · 0.6% of its reports
Splenomegaly after Doxycycline 33 reports · 0.8% of its reports
Splenomegaly after Enrofloxacin (Baytril) 30 reports · 0.8% of its reports

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