Unclassifiable adverse event after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

70 reports to the FDA describe unclassifiable adverse event in dogs given Milbemycin Oxime + Praziquantel. That is 0.2% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported unusually often with this medicine.

70Reports
41%Marked serious
13%Recovered
10%Died or euthanised
23 daysTypical onset
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How soon it started

Same day
16 34%
1–2 days
2 4.3%
3–7 days
4 8.5%
1–4 weeks
2 4.3%
Over a month
23 49%

How the animals did

Recovered
8 11%
Recovered with lasting effects
1 1.4%
Still unwell when reported
12 17%
Died
3 4.3%
Euthanised
4 5.7%
Not known
42 60%

Problems reported at the same time

Age of the animals

Under 1 year
8
1–3 years
17
4–7 years
9
8–11 years
18
12+ years
10

About this medicine

Milbemycin Oxime prevents heartworm and controls some intestinal worms (monthly). Praziquantel treats tapeworms.

Products with this combination include Interceptor Plus. 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 + Praziquantel cause unclassifiable adverse event in dogs?
70 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 23 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).

Unclassifiable adverse event with similar medicines

All reported side effects of Milbemycin Oxime + Praziquantel in dogs · Medicines most reported with unclassifiable adverse event