Inappropriate urination after Afoxolaner (NexGard) in dogs

The FDA has received 472 reports of inappropriate urination in dogs after Afoxolaner. That is 0.8% of all reports for this medicine, compared with 0.5% across reports for all dog medicines, so it is reported unusually often with this medicine.

472Reports
51%Marked serious
35%Recovered
8.5%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
128 32%
1–2 days
78 20%
3–7 days
47 12%
1–4 weeks
68 17%
Over a month
76 19%

How the animals did

Recovered
165 35%
Still unwell when reported
47 10.0%
Died
17 3.6%
Euthanised
23 4.9%
Not known
220 47%

Problems reported at the same time

Age of the animals

Under 1 year
83
1–3 years
127
4–7 years
110
8–11 years
85
12+ years
58

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 inappropriate urination in dogs?
472 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 2 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).

Inappropriate urination with similar medicines

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