Tarry or black stool after Pimobendan (Vetmedin) in dogs

The FDA has received 27 reports of tarry or black stool in dogs after Pimobendan. That is 0.5% 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.

27Reports

56%Marked serious

30%Recovered

19%Died or euthanised

11 daysTypical onset

How soon it started

Same day

0 0.0%

1–2 days

4 20%

3–7 days

3 15%

1–4 weeks

7 35%

Over a month

6 30%

How the animals did

Recovered

8 30%

Still unwell when reported

5 19%

Died

4 15%

Euthanised

1 3.7%

Not known

9 33%

Problems reported at the same time

17 63%

14 52%

10 37%

9 33%

5 19%

4 15%

4 15%

3 11%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Pimobendan treats heart failure and some heart disease.

Products with this ingredient include Vetmedin. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Questions owners ask

Can Pimobendan cause tarry or black stool in dogs?: 27 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 11 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 Pimobendan in dogs · Medicines most reported with tarry or black stool