Musculoskeletal disorder after Milbemycin Oxime + Spinosad (Trifexis) in dogs

352 reports to the FDA describe musculoskeletal disorder in dogs given Milbemycin Oxime + Spinosad. That is 0.3% of all reports for this medicine, compared with 0.3% across reports for all dog medicines.

352Reports

64%Marked serious

32%Recovered

13%Died or euthanised

16 daysTypical onset

How soon it started

Same day

61 32%

1–2 days

18 9.3%

3–7 days

9 4.7%

1–4 weeks

14 7.3%

Over a month

91 47%

How the animals did

Recovered

71 20%

Recovered with lasting effects

42 12%

Still unwell when reported

88 25%

Died

16 4.5%

Euthanised

29 8.2%

Not known

106 30%

Problems reported at the same time

95 27%

91 26%

59 17%

50 14%

Didn't prevent heartworm

50 14%

Tremors

48 14%

Death

42 12%

Breathing problems

39 11%

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 musculoskeletal disorder in dogs?: 352 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 16 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).

Musculoskeletal disorder with similar medicines

Musculoskeletal disorder after Ivermectin + Pyrantel (Heartgard Plus) 197 reports · 0.1% of its reports
Musculoskeletal disorder after Moxidectin (ProHeart 6) 127 reports · 0.3% of its reports
Musculoskeletal disorder after Milbemycin Oxime + Praziquantel (Interceptor Plus) 92 reports · 0.3% of its reports
Musculoskeletal disorder after Milbemycin Oxime (Interceptor) 60 reports · 0.2% of its reports
Musculoskeletal disorder after Selamectin (Revolution) 61 reports · 0.2% of its reports
Musculoskeletal disorder after Ivermectin (Heartgard) 53 reports · 0.4% of its reports

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