Dilated pupils after Moxidectin (ProHeart 6) in dogs

The FDA has received 79 reports of dilated pupils in dogs after Moxidectin. That is 0.2% of all reports for this medicine, compared with 0.1% across reports for all dog medicines.

79Reports

75%Marked serious

15%Recovered

22%Died or euthanised

Same dayTypical onset

How soon it started

Same day

46 61%

1–2 days

10 13%

3–7 days

7 9.3%

1–4 weeks

2 2.7%

Over a month

10 13%

How the animals did

Recovered

12 15%

Still unwell when reported

45 57%

Died

11 14%

Euthanised

6 7.6%

Not known

5 6.3%

Problems reported at the same time

29 37%

29 37%

26 33%

25 32%

20 25%

18 23%

17 22%

17 22%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Moxidectin prevents heartworm disease (monthly topical, or a 6- or 12-month injection for dogs).

Products with this ingredient include ProHeart 6, ProHeart 12. 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 Moxidectin cause dilated pupils in dogs?: 79 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).

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 Milbemycin Oxime + Praziquantel (Interceptor Plus) 56 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 Moxidectin in dogs · Medicines most reported with dilated pupils