Fixed pupil after Moxidectin (ProHeart 6) in dogs

32 reports to the FDA describe fixed pupil in dogs given Moxidectin. That is 0.1% 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.

32Reports
41%Marked serious
0.0%Recovered
53%Died or euthanised
Same dayTypical onset
SponsoredWorried about your pet? Ask a veterinarian online, 24/7

How soon it started

Same day
9 69%
1–2 days
2 15%
3–7 days
1 7.7%
1–4 weeks
0 0.0%
Over a month
1 7.7%

How the animals did

Still unwell when reported
3 9.4%
Died
15 47%
Euthanised
2 6.3%
Not known
12 38%

Problems reported at the same time

Age of the animals

Under 1 year
4
1–3 years
15
4–7 years
7
8–11 years
5
12+ years
1

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 fixed pupil in dogs?
32 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).

Fixed pupil with similar medicines

All reported side effects of Moxidectin in dogs · Medicines most reported with fixed pupil