Leucopenia after Spinosad (Comfortis) in dogs

69 reports to the FDA describe leucopenia in dogs given Spinosad. That is 0.1% of all reports for this medicine, compared with 0.3% across reports for all dog medicines, so it is reported less often than average with this medicine.

69Reports

42%Marked serious

17%Recovered

26%Died or euthanised

7 daysTypical onset

How soon it started

Same day

7 29%

1–2 days

4 17%

3–7 days

2 8.3%

1–4 weeks

1 4.2%

Over a month

10 42%

How the animals did

Recovered

3 4.3%

Recovered with lasting effects

9 13%

Still unwell when reported

12 17%

Died

15 22%

Euthanised

3 4.3%

Not known

27 39%

Problems reported at the same time

41 59%

34 49%

31 45%

30 43%

27 39%

17 25%

16 23%

14 20%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Spinosad kills fleas; monthly chewable.

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

Questions owners ask

Can Spinosad cause leucopenia in dogs?: 69 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).

Leucopenia with similar medicines

Leucopenia after Lufenuron + Milbemycin Oxime (Sentinel) 28 reports · 0.1% of its reports

All reported side effects of Spinosad in dogs · Medicines most reported with leucopenia