Breathing problems after Afoxolaner (NexGard) in dogs

The FDA has received 2,006 reports of breathing problems in dogs after Afoxolaner. That is 3.5% of all reports for this medicine, compared with 2.7% across reports for all dog medicines.

2,006Reports

55%Marked serious

31%Recovered

9.6%Died or euthanised

Same dayTypical onset

How soon it started

Same day

908 53%

1–2 days

329 19%

3–7 days

99 5.8%

1–4 weeks

144 8.4%

Over a month

236 14%

How the animals did

Recovered

622 31%

Still unwell when reported

177 8.8%

Died

112 5.6%

Euthanised

81 4.0%

Not known

1,014 51%

Problems reported at the same time

Itching

670 33%

Lethargy

475 24%

Restlessness or agitation

363 18%

356 18%

343 17%

279 14%

239 12%

212 11%

Age of the animals

Under 1 year

181

1–3 years

406

4–7 years

544

8–11 years

533

12+ years

263

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 breathing problems in dogs?: 2,006 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 the same day 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).

Breathing problems with similar medicines

Breathing problems after Fluralaner (Bravecto) 1,400 reports · 2.0% of its reports
Breathing problems after Sarolaner (Simparica) 467 reports · 2.8% of its reports
Breathing problems after Lotilaner (Credelio) 242 reports · 2.4% of its reports
Breathing problems after Afoxolaner + Moxidectin + Pyrantel (NexGard PLUS) 175 reports · 1.9% of its reports
Breathing problems after Lotilaner + Moxidectin + Praziquantel + Pyrantel (Credelio Quattro) 59 reports · 1.9% of its reports

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