Neutrophilia after Milbemycin Oxime + Spinosad (Trifexis) in dogs

440 reports to the FDA describe neutrophilia in dogs given Milbemycin Oxime + Spinosad. That is 0.3% of all reports for this medicine, compared with 0.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

440Reports

86%Marked serious

32%Recovered

27%Died or euthanised

9 daysTypical onset

How soon it started

Same day

90 28%

1–2 days

45 14%

3–7 days

22 6.9%

1–4 weeks

41 13%

Over a month

120 38%

How the animals did

Recovered

75 17%

Recovered with lasting effects

67 15%

Still unwell when reported

86 20%

Died

52 12%

Euthanised

67 15%

Not known

93 21%

Problems reported at the same time

243 55%

232 53%

228 52%

225 51%

224 51%

131 30%

127 29%

114 26%

Age of the animals

Under 1 year

1–3 years

103

4–7 years

134

8–11 years

107

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 neutrophilia in dogs?: 440 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 9 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).

Neutrophilia with similar medicines

Neutrophilia after Ivermectin + Pyrantel (Heartgard Plus) 327 reports · 0.2% of its reports
Neutrophilia after Moxidectin (ProHeart 6) 429 reports · 0.8% of its reports
Neutrophilia after Milbemycin Oxime + Praziquantel (Interceptor Plus) 133 reports · 0.4% of its reports
Neutrophilia after Milbemycin Oxime (Interceptor) 56 reports · 0.2% of its reports
Neutrophilia after Selamectin (Revolution) 75 reports · 0.3% of its reports
Neutrophilia after Ivermectin (Heartgard) 69 reports · 0.6% of its reports
Neutrophilia after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 20 reports · 0.2% of its reports

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