Pyoderma after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 166 reports of pyoderma in dogs after Milbemycin Oxime + Spinosad. That is 0.1% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported less often than average with this medicine.

166Reports

30%Marked serious

38%Recovered

3.6%Died or euthanised

32 daysTypical onset

How soon it started

Same day

30 24%

1–2 days

10 8.0%

3–7 days

5 4.0%

1–4 weeks

15 12%

Over a month

65 52%

How the animals did

Recovered

30 18%

Recovered with lasting effects

33 20%

Still unwell when reported

48 29%

Died

3 1.8%

Euthanised

3 1.8%

Not known

49 30%

Problems reported at the same time

Itching

52 31%

Vomiting

39 23%

Hair loss

36 22%

Skin rash or irritation

31 19%

Didn't work as expected

28 17%

Lethargy

22 13%

Skin redness

15 9.0%

Diarrhea

15 9.0%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Milbemycin Oxime prevents heartworm and controls some intestinal worms (monthly). Spinosad kills fleas; monthly chewable.

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

Some herding breeds (for example Collies) carry the MDR1 gene variant and can be more sensitive to this drug class at high doses.

Questions owners ask

Can Milbemycin Oxime + Spinosad cause pyoderma in dogs?: 166 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 32 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).

Pyoderma with similar medicines

Pyoderma after Ivermectin + Pyrantel (Heartgard Plus) 61 reports · 0.0% of its reports
Pyoderma after Moxidectin (ProHeart 6) 67 reports · 0.1% of its reports
Pyoderma after Milbemycin Oxime + Praziquantel (Interceptor Plus) 38 reports · 0.1% of its reports
Pyoderma after Milbemycin Oxime (Interceptor) 28 reports · 0.1% of its reports
Pyoderma after Selamectin (Revolution) 101 reports · 0.3% of its reports
Pyoderma after Ivermectin (Heartgard) 28 reports · 0.2% of its reports

All reported side effects of Milbemycin Oxime + Spinosad in dogs · Medicines most reported with pyoderma