Otitis after Milbemycin Oxime + Spinosad (Trifexis) in dogs

137 reports to the FDA describe otitis in dogs given Milbemycin Oxime + 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 unusually often with this medicine.

137Reports
35%Marked serious
34%Recovered
1.5%Died or euthanised
90 daysTypical onset
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How soon it started

Same day
20 23%
1–2 days
2 2.3%
3–7 days
1 1.1%
1–4 weeks
8 9.2%
Over a month
56 64%

How the animals did

Recovered
34 25%
Recovered with lasting effects
13 9.5%
Still unwell when reported
32 23%
Died
1 0.7%
Euthanised
1 0.7%
Not known
56 41%

Problems reported at the same time

Age of the animals

Under 1 year
21
1–3 years
47
4–7 years
36
8–11 years
22
12+ years
11

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 otitis in dogs?
137 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 90 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).

Otitis with similar medicines

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