Decreased haemoglobin after Metronidazole in dogs

36 reports to the FDA describe decreased haemoglobin in dogs given Metronidazole. That is 1.2% 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.

36Reports

92%Marked serious

14%Recovered

31%Died or euthanised

10 daysTypical onset

How soon it started

Same day

3 11%

1–2 days

1 3.7%

3–7 days

5 19%

1–4 weeks

9 33%

Over a month

9 33%

How the animals did

Recovered

4 11%

Recovered with lasting effects

1 2.8%

Still unwell when reported

13 36%

Died

1 2.8%

Euthanised

10 28%

Not known

7 19%

Problems reported at the same time

22 61%

22 61%

18 50%

18 50%

18 50%

18 50%

15 42%

Decreased red blood cell count

13 36%

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 decreased haemoglobin in dogs?: 36 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 10 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).

Decreased haemoglobin with similar medicines

Decreased haemoglobin after Amoxicillin + Clavulanate (Clavamox) 40 reports · 0.7% of its reports
Decreased haemoglobin after Doxycycline 42 reports · 1.0% of its reports
Decreased haemoglobin after Enrofloxacin (Baytril) 35 reports · 0.9% of its reports

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