Labeled drug-species interaction after Ivermectin (Heartgard) in dogs

The FDA has received 121 reports of labeled drug-species interaction in dogs after Ivermectin. That is 1.0% 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.

121Reports
47%Marked serious
33%Recovered
9.9%Died or euthanised
59 daysTypical onset
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How soon it started

Same day
2 13%
1–2 days
2 13%
3–7 days
1 6.7%
1–4 weeks
1 6.7%
Over a month
9 60%

How the animals did

Recovered
19 16%
Recovered with lasting effects
21 17%
Still unwell when reported
9 7.4%
Died
7 5.8%
Euthanised
5 4.1%
Not known
60 50%

Problems reported at the same time

Age of the animals

Under 1 year
24
1–3 years
50
4–7 years
23
8–11 years
15
12+ years
2

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 labeled drug-species interaction in dogs?
121 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 59 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).

All reported side effects of Ivermectin in dogs · Medicines most reported with labeled drug-species interaction