Unpalatable after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 2,574 reports of unpalatable in dogs after Milbemycin Oxime + Spinosad. That is 2.0% of all reports for this medicine, compared with 0.6% across reports for all dog medicines, so it is reported unusually often with this medicine.

2,574Reports

8.7%Marked serious

61%Recovered

2.8%Died or euthanised

1 daysTypical onset

How soon it started

Same day

564 49%

1–2 days

39 3.4%

3–7 days

18 1.6%

1–4 weeks

80 6.9%

Over a month

460 40%

How the animals did

Recovered

1,465 57%

Recovered with lasting effects

98 3.8%

Still unwell when reported

155 6.0%

Died

44 1.7%

Euthanised

28 1.1%

Not known

784 30%

Problems reported at the same time

Vomiting

1,563 61%

Didn't stop fleas

450 17%

Didn't work as expected

329 13%

Lethargy

317 12%

Odor, abnormal

191 7.4%

Didn't prevent heartworm

164 6.4%

Itching

155 6.0%

Loss of appetite

140 5.4%

Age of the animals

Under 1 year

187

1–3 years

952

4–7 years

740

8–11 years

321

12+ years

145

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 unpalatable in dogs?: 2,574 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).

Unpalatable with similar medicines

Unpalatable after Ivermectin + Pyrantel (Heartgard Plus) 647 reports · 0.4% of its reports
Unpalatable after Milbemycin Oxime + Praziquantel (Interceptor Plus) 183 reports · 0.6% of its reports
Unpalatable after Milbemycin Oxime (Interceptor) 45 reports · 0.2% of its reports
Unpalatable after Ivermectin (Heartgard) 84 reports · 0.7% of its reports

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