Eye disorder (for photophobia see 'neurological') after Ivermectin (Heartgard) in dogs

The FDA has received 65 reports of eye disorder (for photophobia see 'neurological') in dogs after Ivermectin. That is 0.5% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

65Reports
45%Marked serious
32%Recovered
6.2%Died or euthanised
64 daysTypical onset
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How soon it started

Same day
6 15%
1–2 days
3 7.7%
3–7 days
4 10%
1–4 weeks
3 7.7%
Over a month
23 59%

How the animals did

Recovered
14 22%
Recovered with lasting effects
7 11%
Still unwell when reported
12 18%
Died
1 1.5%
Euthanised
3 4.6%
Not known
28 43%

Problems reported at the same time

Eye or vision problems
22 34%
Vomiting
15 23%
Lethargy
14 22%
Wobbliness (ataxia)
11 17%
Behaviour change
10 15%
Tremors
8 12%
Abnormal menace reflex test
8 12%
Skin redness
7 11%

Age of the animals

Under 1 year
15
1–3 years
14
4–7 years
13
8–11 years
16
12+ years
4

About this medicine

Ivermectin prevents heartworm disease (monthly).

Products with this ingredient include Heartgard. 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 Ivermectin cause eye disorder (for photophobia see 'neurological') in dogs?
65 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 64 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).

Eye disorder (for photophobia see 'neurological') with similar medicines

All reported side effects of Ivermectin in dogs · Medicines most reported with eye disorder (for photophobia see 'neurological')