Stumbling gait after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 236 reports of stumbling gait in dogs after Milbemycin Oxime + Spinosad. That is 0.2% of all reports for this medicine, compared with 0.2% across reports for all dog medicines.

236Reports

45%Marked serious

56%Recovered

8.9%Died or euthanised

1 daysTypical onset

How soon it started

Same day

82 47%

1–2 days

23 13%

3–7 days

6 3.4%

1–4 weeks

14 8.0%

Over a month

51 29%

How the animals did

Recovered

112 47%

Recovered with lasting effects

20 8.5%

Still unwell when reported

28 12%

Died

13 5.5%

Euthanised

8 3.4%

Not known

55 23%

Problems reported at the same time

119 50%

69 29%

50 21%

50 21%

37 16%

36 15%

35 15%

30 13%

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 stumbling gait in dogs?: 236 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).

Stumbling gait with similar medicines

Stumbling gait after Ivermectin + Pyrantel (Heartgard Plus) 152 reports · 0.1% of its reports
Stumbling gait after Moxidectin (ProHeart 6) 78 reports · 0.2% of its reports
Stumbling gait after Milbemycin Oxime + Praziquantel (Interceptor Plus) 63 reports · 0.2% of its reports
Stumbling gait after Milbemycin Oxime (Interceptor) 34 reports · 0.1% of its reports
Stumbling gait after Selamectin (Revolution) 32 reports · 0.1% of its reports
Stumbling gait after Ivermectin (Heartgard) 65 reports · 0.5% of its reports

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