Abnormal posture after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 1,182 reports of abnormal posture in dogs after Milbemycin Oxime + Spinosad. That is 0.9% of all reports for this medicine, compared with 0.3% across reports for all dog medicines, so it is reported unusually often with this medicine.

1,182Reports

30%Marked serious

68%Recovered

4.3%Died or euthanised

1 daysTypical onset

How soon it started

Same day

464 49%

1–2 days

81 8.5%

3–7 days

22 2.3%

1–4 weeks

41 4.3%

Over a month

348 36%

How the animals did

Recovered

671 57%

Recovered with lasting effects

137 12%

Still unwell when reported

93 7.9%

Died

22 1.9%

Euthanised

29 2.5%

Not known

230 19%

Problems reported at the same time

627 53%

438 37%

343 29%

273 23%

220 19%

159 13%

151 13%

137 12%

Age of the animals

Under 1 year

226

1–3 years

536

4–7 years

236

8–11 years

112

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 abnormal posture in dogs?: 1,182 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).

Abnormal posture with similar medicines

Abnormal posture after Ivermectin + Pyrantel (Heartgard Plus) 139 reports · 0.1% of its reports
Abnormal posture after Moxidectin (ProHeart 6) 61 reports · 0.1% of its reports
Abnormal posture after Milbemycin Oxime + Praziquantel (Interceptor Plus) 32 reports · 0.1% of its reports
Abnormal posture after Milbemycin Oxime (Interceptor) 25 reports · 0.1% of its reports
Abnormal posture after Selamectin (Revolution) 31 reports · 0.1% of its reports
Abnormal posture after Ivermectin (Heartgard) 46 reports · 0.4% of its reports

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