Dehydration after Milbemycin Oxime + Spinosad (Trifexis) in dogs

624 reports to the FDA describe dehydration in dogs given Milbemycin Oxime + Spinosad. That is 0.5% of all reports for this medicine, compared with 0.7% across reports for all dog medicines.

624Reports

64%Marked serious

49%Recovered

14%Died or euthanised

1 daysTypical onset

How soon it started

Same day

174 39%

1–2 days

73 17%

3–7 days

21 4.8%

1–4 weeks

35 7.9%

Over a month

139 31%

How the animals did

Recovered

234 38%

Recovered with lasting effects

74 12%

Still unwell when reported

83 13%

Died

42 6.7%

Euthanised

48 7.7%

Not known

143 23%

Problems reported at the same time

422 68%

407 65%

329 53%

223 36%

166 27%

108 17%

100 16%

98 16%

Age of the animals

Under 1 year

1–3 years

212

4–7 years

154

8–11 years

103

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 dehydration in dogs?: 624 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).

Dehydration with similar medicines

Dehydration after Ivermectin + Pyrantel (Heartgard Plus) 322 reports · 0.2% of its reports
Dehydration after Moxidectin (ProHeart 6) 408 reports · 0.8% of its reports
Dehydration after Milbemycin Oxime + Praziquantel (Interceptor Plus) 133 reports · 0.4% of its reports
Dehydration after Milbemycin Oxime (Interceptor) 135 reports · 0.5% of its reports
Dehydration after Selamectin (Revolution) 106 reports · 0.4% of its reports
Dehydration after Ivermectin (Heartgard) 93 reports · 0.8% of its reports
Dehydration after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 32 reports · 0.4% of its reports

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