Leucocytosis after Sarolaner (Simparica) in dogs

112 reports to the FDA describe leucocytosis in dogs given Sarolaner. That is 0.7% of all reports for this medicine, compared with 1.0% across reports for all dog medicines, so it is reported less often than average with this medicine.

112Reports
72%Marked serious
8.9%Recovered
20%Died or euthanised
1 daysTypical onset
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How soon it started

Same day
37 37%
1–2 days
25 25%
3–7 days
13 13%
1–4 weeks
12 12%
Over a month
12 12%

How the animals did

Recovered
10 8.9%
Still unwell when reported
71 63%
Died
9 8.0%
Euthanised
13 12%
Not known
9 8.0%

Problems reported at the same time

Age of the animals

Under 1 year
11
1–3 years
21
4–7 years
28
8–11 years
37
12+ years
15

About this medicine

Sarolaner kills fleas, ticks and some mites; monthly.

Products with this ingredient include Simparica. 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 Sarolaner cause leucocytosis in dogs?
112 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 1 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).

Leucocytosis with similar medicines

All reported side effects of Sarolaner in dogs · Medicines most reported with leucocytosis