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

The FDA has received 218 reports of unsteady gait in dogs after Milbemycin Oxime + Spinosad. That is 0.2% of all reports for this medicine, compared with 0.1% across reports for all dog medicines.

218Reports
33%Marked serious
60%Recovered
5.5%Died or euthanised
1 daysTypical onset
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How soon it started

Same day
68 40%
1–2 days
26 15%
3–7 days
1 0.6%
1–4 weeks
14 8.3%
Over a month
60 36%

How the animals did

Recovered
101 46%
Recovered with lasting effects
30 14%
Still unwell when reported
27 12%
Died
7 3.2%
Euthanised
5 2.3%
Not known
48 22%

Problems reported at the same time

Age of the animals

Under 1 year
49
1–3 years
49
4–7 years
53
8–11 years
38
12+ years
24

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 unsteady gait in dogs?
218 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).

Unsteady gait with similar medicines

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