Thrombocytosis after Fenbendazole in dogs

20 reports to the FDA describe thrombocytosis in dogs given Fenbendazole. That is 0.3% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

20Reports

90%Marked serious

15%Recovered

5.0%Died or euthanised

11 daysTypical onset

How soon it started

Same day

2 11%

1–2 days

3 17%

3–7 days

3 17%

1–4 weeks

6 33%

Over a month

4 22%

How the animals did

Recovered

3 15%

Still unwell when reported

7 35%

Euthanised

1 5.0%

Not known

9 45%

Problems reported at the same time

12 60%

10 50%

8 40%

7 35%

7 35%

6 30%

Hyponatremia

6 30%

Monocytosis

6 30%

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 thrombocytosis in dogs?: 20 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).

Thrombocytosis with similar medicines

Thrombocytosis after Pyrantel + Sarolaner (Simparica Trio) 33 reports · 0.1% of its reports

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