Hyperkalaemia after Milbemycin Oxime + Spinosad (Trifexis) in dogs

99 reports to the FDA describe hyperkalaemia in dogs given Milbemycin Oxime + Spinosad. That is 0.1% of all reports for this medicine, compared with 0.3% across reports for all dog medicines, so it is reported less often than average with this medicine.

99Reports
83%Marked serious
38%Recovered
26%Died or euthanised
21 daysTypical onset
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How soon it started

Same day
20 29%
1–2 days
8 11%
3–7 days
4 5.7%
1–4 weeks
6 8.6%
Over a month
32 46%

How the animals did

Recovered
19 19%
Recovered with lasting effects
19 19%
Still unwell when reported
18 18%
Died
10 10%
Euthanised
16 16%
Not known
17 17%

Problems reported at the same time

Age of the animals

Under 1 year
17
1–3 years
24
4–7 years
18
8–11 years
25
12+ years
14

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 hyperkalaemia in dogs?
99 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).

Hyperkalaemia with similar medicines

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