Dental disease after Milbemycin Oxime + Spinosad (Trifexis) in dogs

125 reports to the FDA describe dental disease 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.

125Reports
49%Marked serious
19%Recovered
9.6%Died or euthanised
41 daysTypical onset
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How soon it started

Same day
17 36%
1–2 days
1 2.1%
3–7 days
0 0.0%
1–4 weeks
4 8.5%
Over a month
25 53%

How the animals did

Recovered
14 11%
Recovered with lasting effects
10 8.0%
Still unwell when reported
32 26%
Died
7 5.6%
Euthanised
5 4.0%
Not known
57 46%

Problems reported at the same time

Age of the animals

Under 1 year
3
1–3 years
20
4–7 years
30
8–11 years
48
12+ years
23

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 dental disease in dogs?
125 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 41 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).

Dental disease with similar medicines

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