Arthritis after Spinosad (Comfortis) in dogs

79 reports to the FDA describe arthritis in dogs given Spinosad. That is 0.1% of all reports for this medicine, compared with 0.2% across reports for all dog medicines.

79Reports

86%Marked serious

34%Recovered

23%Died or euthanised

6 daysTypical onset

How soon it started

Same day

15 50%

1–2 days

0 0.0%

3–7 days

1 3.3%

1–4 weeks

2 6.7%

Over a month

12 40%

How the animals did

Recovered

3 3.8%

Recovered with lasting effects

24 30%

Still unwell when reported

25 32%

Died

3 3.8%

Euthanised

15 19%

Not known

9 11%

Problems reported at the same time

30 38%

19 24%

16 20%

13 16%

12 15%

10 13%

9 11%

8 10%

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 arthritis in dogs?: 79 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 6 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).

Arthritis with similar medicines

Arthritis after Lufenuron + Milbemycin Oxime (Sentinel) 27 reports · 0.1% of its reports

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