Dilated pupils after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

The FDA has received 56 reports of dilated pupils in dogs after Milbemycin Oxime + Praziquantel. That is 0.2% of all reports for this medicine, compared with 0.1% across reports for all dog medicines.

56Reports

43%Marked serious

34%Recovered

13%Died or euthanised

4 daysTypical onset

How soon it started

Same day

16 33%

1–2 days

8 17%

3–7 days

3 6.3%

1–4 weeks

2 4.2%

Over a month

19 40%

How the animals did

Recovered

19 34%

Still unwell when reported

17 30%

Died

6 11%

Euthanised

1 1.8%

Not known

13 23%

Problems reported at the same time

16 29%

12 21%

12 21%

12 21%

10 18%

9 16%

8 14%

8 14%

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). 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 dilated pupils in dogs?: 56 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 4 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).

Dilated pupils with similar medicines

Dilated pupils after Ivermectin + Pyrantel (Heartgard Plus) 136 reports · 0.1% of its reports
Dilated pupils after Milbemycin Oxime + Spinosad (Trifexis) 234 reports · 0.2% of its reports
Dilated pupils after Moxidectin (ProHeart 6) 79 reports · 0.2% of its reports
Dilated pupils after Milbemycin Oxime (Interceptor) 23 reports · 0.1% of its reports
Dilated pupils after Selamectin (Revolution) 26 reports · 0.1% of its reports
Dilated pupils after Ivermectin (Heartgard) 87 reports · 0.7% of its reports
Dilated pupils after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 21 reports · 0.2% of its reports

All reported side effects of Milbemycin Oxime + Praziquantel in dogs · Medicines most reported with dilated pupils