Neutropenia after Afoxolaner (NexGard) in dogs

The FDA has received 99 reports of neutropenia in dogs after Afoxolaner. That is 0.2% of all reports for this medicine, compared with 0.2% across reports for all dog medicines.

99Reports
58%Marked serious
22%Recovered
14%Died or euthanised
12 daysTypical onset
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How soon it started

Same day
12 17%
1–2 days
15 21%
3–7 days
5 7.0%
1–4 weeks
12 17%
Over a month
27 38%

How the animals did

Recovered
22 22%
Still unwell when reported
30 30%
Died
7 7.1%
Euthanised
7 7.1%
Not known
33 33%

Problems reported at the same time

Age of the animals

Under 1 year
12
1–3 years
28
4–7 years
25
8–11 years
28
12+ years
5

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 neutropenia in dogs?
99 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 12 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).

Neutropenia with similar medicines

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