Abnormal radiograph finding after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 630 reports of abnormal radiograph finding in dogs after Milbemycin Oxime + Spinosad. That is 0.5% of all reports for this medicine, compared with 0.9% across reports for all dog medicines, so it is reported less often than average with this medicine.

630Reports

82%Marked serious

32%Recovered

28%Died or euthanised

7 daysTypical onset

How soon it started

Same day

108 26%

1–2 days

69 17%

3–7 days

38 9.1%

1–4 weeks

40 9.6%

Over a month

162 39%

How the animals did

Recovered

116 18%

Recovered with lasting effects

87 14%

Still unwell when reported

125 20%

Died

71 11%

Euthanised

106 17%

Not known

125 20%

Problems reported at the same time

305 48%

296 47%

253 40%

194 31%

174 28%

151 24%

145 23%

107 17%

Age of the animals

Under 1 year

1–3 years

142

4–7 years

176

8–11 years

172

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 radiograph finding in dogs?: 630 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 7 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).

Abnormal radiograph finding with similar medicines

Abnormal radiograph finding after Ivermectin + Pyrantel (Heartgard Plus) 505 reports · 0.3% of its reports
Abnormal radiograph finding after Moxidectin (ProHeart 6) 498 reports · 1.0% of its reports
Abnormal radiograph finding after Milbemycin Oxime + Praziquantel (Interceptor Plus) 164 reports · 0.5% of its reports
Abnormal radiograph finding after Milbemycin Oxime (Interceptor) 138 reports · 0.5% of its reports
Abnormal radiograph finding after Selamectin (Revolution) 149 reports · 0.5% of its reports
Abnormal radiograph finding after Ivermectin (Heartgard) 103 reports · 0.9% of its reports
Abnormal radiograph finding after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 52 reports · 0.6% of its reports

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