Monocytosis after Lotilaner (Credelio) in dogs

59 reports to the FDA describe monocytosis in dogs given Lotilaner. That is 0.6% of all reports for this medicine, compared with 0.3% across reports for all dog medicines, so it is reported unusually often with this medicine.

59Reports
76%Marked serious
12%Recovered
22%Died or euthanised
22 daysTypical onset
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How soon it started

Same day
5 11%
1–2 days
9 19%
3–7 days
4 8.5%
1–4 weeks
7 15%
Over a month
22 47%

How the animals did

Recovered
7 12%
Still unwell when reported
19 32%
Died
5 8.5%
Euthanised
8 14%
Not known
20 34%

Problems reported at the same time

Age of the animals

Under 1 year
25
1–3 years
10
4–7 years
16
8–11 years
6
12+ years
2

About this medicine

Lotilaner kills fleas and ticks; monthly chewable.

Products with this ingredient include Credelio. 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 Lotilaner cause monocytosis in dogs?
59 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 22 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).

Monocytosis with similar medicines

All reported side effects of Lotilaner in dogs · Medicines most reported with monocytosis