Bone and joint disorder after Spinosad (Comfortis) in dogs

The FDA has received 40 reports of bone and joint disorder in dogs after Spinosad. That is 0.1% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported less often than average with this medicine.

40Reports

75%Marked serious

38%Recovered

25%Died or euthanised

43 daysTypical onset

How soon it started

Same day

6 26%

1–2 days

1 4.3%

3–7 days

2 8.7%

1–4 weeks

1 4.3%

Over a month

13 57%

How the animals did

Recovered

3 7.5%

Recovered with lasting effects

12 30%

Still unwell when reported

7 18%

Died

4 10%

Euthanised

6 15%

Not known

8 20%

Problems reported at the same time

13 33%

9 23%

8 20%

6 15%

5 13%

5 13%

5 13%

4 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 bone and joint disorder in dogs?: 40 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 43 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 Spinosad in dogs · Medicines most reported with bone and joint disorder