Mucous stool after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 180 reports of mucous stool in dogs after Milbemycin Oxime + Spinosad. That is 0.1% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported less often than average with this medicine.

180Reports

38%Marked serious

47%Recovered

7.2%Died or euthanised

3 daysTypical onset

How soon it started

Same day

44 31%

1–2 days

27 19%

3–7 days

4 2.8%

1–4 weeks

17 12%

Over a month

51 36%

How the animals did

Recovered

48 27%

Recovered with lasting effects

36 20%

Still unwell when reported

36 20%

Died

6 3.3%

Euthanised

7 3.9%

Not known

47 26%

Problems reported at the same time

110 61%

97 54%

81 45%

73 41%

33 18%

Didn't work as expected

30 17%

Liver problems

26 14%

Blood in faeces

24 13%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

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 mucous stool in dogs?: 180 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 3 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).

Mucous stool with similar medicines

Mucous stool after Ivermectin + Pyrantel (Heartgard Plus) 258 reports · 0.2% of its reports
Mucous stool after Moxidectin (ProHeart 6) 81 reports · 0.2% of its reports
Mucous stool after Milbemycin Oxime + Praziquantel (Interceptor Plus) 91 reports · 0.3% of its reports
Mucous stool after Milbemycin Oxime (Interceptor) 82 reports · 0.3% of its reports
Mucous stool after Selamectin (Revolution) 41 reports · 0.1% of its reports
Mucous stool after Ivermectin (Heartgard) 27 reports · 0.2% of its reports

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