Decreased haematocrit after Fenbendazole in dogs

23 reports to the FDA describe decreased haematocrit in dogs given Fenbendazole. That is 0.4% 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.

23Reports

91%Marked serious

0.0%Recovered

13%Died or euthanised

13 daysTypical onset

How soon it started

Same day

0 0.0%

1–2 days

4 17%

3–7 days

5 22%

1–4 weeks

9 39%

Over a month

5 22%

How the animals did

Still unwell when reported

13 57%

Died

1 4.3%

Euthanised

2 8.7%

Not known

7 30%

Problems reported at the same time

13 57%

11 48%

11 48%

9 39%

Decreased haemoglobin

8 35%

Neutropenia

8 35%

Diarrhea

8 35%

Hypoalbuminaemia

8 35%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Fenbendazole treats intestinal worms and some other parasites.

Questions owners ask

Can Fenbendazole cause decreased haematocrit in dogs?: 23 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 13 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 haematocrit with similar medicines

Decreased haematocrit after Pyrantel + Sarolaner (Simparica Trio) 29 reports · 0.1% of its reports

All reported side effects of Fenbendazole in dogs · Medicines most reported with decreased haematocrit