Dilated pupils after Imidacloprid + Moxidectin (Advantage Multi) in dogs

The FDA has received 56 reports of dilated pupils in dogs after Imidacloprid + Moxidectin. That is 0.4% 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.

56Reports
82%Marked serious
50%Recovered
3.6%Died or euthanised
Same dayTypical onset
SponsoredWorried about your pet? Ask a veterinarian online, 24/7

How soon it started

Same day
30 57%
1–2 days
20 38%
3–7 days
1 1.9%
1–4 weeks
1 1.9%
Over a month
1 1.9%

How the animals did

Recovered
28 50%
Still unwell when reported
6 11%
Euthanised
2 3.6%
Not known
20 36%

Problems reported at the same time

Age of the animals

Under 1 year
7
1–3 years
20
4–7 years
16
8–11 years
8
12+ years
1

About this medicine

Imidacloprid kills fleas (spot-on or collar). Moxidectin prevents heartworm disease (monthly topical, or a 6- or 12-month injection for dogs).

Products with this combination include Advantage Multi. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Questions owners ask

Can Imidacloprid + Moxidectin 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 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

All reported side effects of Imidacloprid + Moxidectin in dogs · Medicines most reported with dilated pupils