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

The FDA has received 45 reports of autoimmune disorder in dogs after Milbemycin Oxime + Spinosad. That is 0.0% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported less often than average with this medicine.

45Reports
89%Marked serious
38%Recovered
18%Died or euthanised
21 daysTypical onset
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How soon it started

Same day
9 32%
1–2 days
1 3.6%
3–7 days
0 0.0%
1–4 weeks
7 25%
Over a month
11 39%

How the animals did

Recovered
4 8.9%
Recovered with lasting effects
13 29%
Still unwell when reported
13 29%
Died
3 6.7%
Euthanised
5 11%
Not known
7 16%

Problems reported at the same time

Age of the animals

Under 1 year
1
1–3 years
11
4–7 years
16
8–11 years
8
12+ years
6

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 autoimmune disorder in dogs?
45 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 21 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).

Autoimmune disorder with similar medicines

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