Head shake - ear disorder after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 169 reports of head shake - ear disorder in dogs after Milbemycin Oxime + Spinosad. That is 0.1% of all reports for this medicine, compared with 0.1% across reports for all dog medicines.

169Reports

29%Marked serious

47%Recovered

2.4%Died or euthanised

1 daysTypical onset

How soon it started

Same day

47 38%

1–2 days

18 15%

3–7 days

8 6.5%

1–4 weeks

7 5.7%

Over a month

43 35%

How the animals did

Recovered

57 34%

Recovered with lasting effects

23 14%

Still unwell when reported

29 17%

Died

2 1.2%

Euthanised

2 1.2%

Not known

56 33%

Problems reported at the same time

55 33%

48 28%

40 24%

34 20%

25 15%

18 11%

17 10%

16 9.5%

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 head shake - ear disorder in dogs?: 169 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 1 day 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).

Head shake - ear disorder with similar medicines

Head shake - ear disorder after Ivermectin + Pyrantel (Heartgard Plus) 73 reports · 0.0% of its reports
Head shake - ear disorder after Moxidectin (ProHeart 6) 64 reports · 0.1% of its reports
Head shake - ear disorder after Milbemycin Oxime + Praziquantel (Interceptor Plus) 23 reports · 0.1% of its reports

All reported side effects of Milbemycin Oxime + Spinosad in dogs · Medicines most reported with head shake - ear disorder