Ear infection after Milbemycin Oxime + Spinosad (Trifexis) in dogs

524 reports to the FDA describe ear infection in dogs given Milbemycin Oxime + Spinosad. That is 0.4% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

524Reports

20%Marked serious

31%Recovered

2.9%Died or euthanised

61 daysTypical onset

How soon it started

Same day

83 28%

1–2 days

9 3.0%

3–7 days

6 2.0%

1–4 weeks

29 9.8%

Over a month

170 57%

How the animals did

Recovered

123 23%

Recovered with lasting effects

40 7.6%

Still unwell when reported

130 25%

Died

7 1.3%

Euthanised

8 1.5%

Not known

216 41%

Problems reported at the same time

Vomiting

234 45%

Didn't prevent heartworm

109 21%

Itching

61 12%

Didn't work as expected

55 10%

54 10%

49 9.4%

48 9.2%

35 6.7%

Age of the animals

Under 1 year

1–3 years

203

4–7 years

147

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 ear infection in dogs?: 524 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 61 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).

Ear infection with similar medicines

Ear infection after Ivermectin + Pyrantel (Heartgard Plus) 116 reports · 0.1% of its reports
Ear infection after Moxidectin (ProHeart 6) 34 reports · 0.1% of its reports
Ear infection after Milbemycin Oxime + Praziquantel (Interceptor Plus) 206 reports · 0.7% of its reports
Ear infection after Milbemycin Oxime (Interceptor) 36 reports · 0.1% of its reports
Ear infection after Ivermectin (Heartgard) 36 reports · 0.3% of its reports

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