Defect unknown/not specified after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

The FDA has received 48 reports of defect unknown/not specified in dogs after Milbemycin Oxime + Praziquantel. That is 0.2% of all reports for this medicine, compared with 0.0% across reports for all dog medicines, so it is reported unusually often with this medicine.

48Reports
17%Marked serious
33%Recovered
6.3%Died or euthanised
Same dayTypical onset
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How soon it started

Same day
22 61%
1–2 days
3 8.3%
3–7 days
4 11%
1–4 weeks
2 5.6%
Over a month
5 14%

How the animals did

Recovered
16 33%
Still unwell when reported
5 10%
Euthanised
3 6.3%
Not known
24 50%

Problems reported at the same time

Age of the animals

Under 1 year
1
1–3 years
10
4–7 years
19
8–11 years
14
12+ years
3

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 defect unknown/not specified in dogs?
48 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 the same day 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).

Defect unknown/not specified with similar medicines

All reported side effects of Milbemycin Oxime + Praziquantel in dogs · Medicines most reported with defect unknown/not specified