Cardiac disorder after Afoxolaner (NexGard) in dogs

The FDA has received 55 reports of cardiac disorder in dogs after Afoxolaner. That is 0.1% of all reports for this medicine, compared with 1.1% across reports for all dog medicines, so it is reported less often than average with this medicine.

55Reports
89%Marked serious
13%Recovered
53%Died or euthanised
5 daysTypical onset
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How soon it started

Same day
13 31%
1–2 days
5 12%
3–7 days
7 17%
1–4 weeks
7 17%
Over a month
10 24%

How the animals did

Recovered
5 9.1%
Recovered with lasting effects
2 3.6%
Still unwell when reported
9 16%
Died
18 33%
Euthanised
11 20%
Not known
10 18%

Problems reported at the same time

Age of the animals

Under 1 year
2
1–3 years
9
4–7 years
12
8–11 years
15
12+ years
15

About this medicine

Afoxolaner kills fleas and ticks; given as a monthly chewable.

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

In 2018 the FDA alerted owners and vets that isoxazoline products have been associated with neurologic reactions such as muscle tremors, wobbliness (ataxia) and seizures, including in animals with no history of them.

Questions owners ask

Can Afoxolaner cause cardiac disorder in dogs?
55 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 5 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).

Cardiac disorder with similar medicines

All reported side effects of Afoxolaner in dogs · Medicines most reported with cardiac disorder