Lameness after Afoxolaner (NexGard) in dogs

337 reports to the FDA describe lameness in dogs given Afoxolaner. That is 0.6% of all reports for this medicine, compared with 0.6% across reports for all dog medicines.

337Reports
45%Marked serious
24%Recovered
7.4%Died or euthanised
8 daysTypical onset
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How soon it started

Same day
53 22%
1–2 days
44 18%
3–7 days
23 9.5%
1–4 weeks
45 19%
Over a month
76 32%

How the animals did

Recovered
79 23%
Recovered with lasting effects
2 0.6%
Still unwell when reported
68 20%
Died
10 3.0%
Euthanised
15 4.5%
Not known
163 48%

Problems reported at the same time

Age of the animals

Under 1 year
61
1–3 years
81
4–7 years
81
8–11 years
75
12+ years
31

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 lameness in dogs?
337 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 8 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).

Lameness with similar medicines

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