Abnormal menace reflex test after Ivermectin (Heartgard) in dogs

63 reports to the FDA describe abnormal menace reflex test in dogs given Ivermectin. That is 0.5% 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.

63Reports
83%Marked serious
56%Recovered
3.2%Died or euthanised
32 daysTypical onset
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How soon it started

Same day
12 26%
1–2 days
4 8.5%
3–7 days
2 4.3%
1–4 weeks
5 11%
Over a month
24 51%

How the animals did

Recovered
24 38%
Recovered with lasting effects
11 17%
Still unwell when reported
7 11%
Euthanised
2 3.2%
Not known
19 30%

Problems reported at the same time

Age of the animals

Under 1 year
16
1–3 years
18
4–7 years
20
8–11 years
4
12+ years
5

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 abnormal menace reflex test in dogs?
63 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 32 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).

Abnormal menace reflex test with similar medicines

All reported side effects of Ivermectin in dogs · Medicines most reported with abnormal menace reflex test