Decreased packed cell volume (pcv) after Fenbendazole in dogs

37 reports to the FDA describe decreased packed cell volume (pcv) in dogs given Fenbendazole. That is 0.6% 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.

37Reports

100%Marked serious

19%Recovered

27%Died or euthanised

7 daysTypical onset

How soon it started

Same day

7 25%

1–2 days

4 14%

3–7 days

5 18%

1–4 weeks

6 21%

Over a month

6 21%

How the animals did

Recovered

6 16%

Recovered with lasting effects

1 2.7%

Still unwell when reported

11 30%

Died

2 5.4%

Euthanised

8 22%

Not known

9 24%

Problems reported at the same time

Lethargy

21 57%

Decreased red blood cell count

16 43%

Blood problems

14 38%

Loss of appetite

12 32%

Liver problems

11 30%

Decreased haemoglobin

10 27%

Vomiting

10 27%

Leucocytosis

10 27%

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 packed cell volume (pcv) in dogs?: 37 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 7 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 Fenbendazole in dogs · Medicines most reported with decreased packed cell volume (pcv)