Abnormal radiograph finding after Selamectin (Revolution) in cats

170 reports to the FDA describe abnormal radiograph finding in cats given Selamectin. That is 0.8% of all reports for this medicine, compared with 1.0% across reports for all cat medicines.

170Reports
32%Marked serious
4.1%Recovered
34%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
21 28%
1–2 days
22 29%
3–7 days
13 17%
1–4 weeks
9 12%
Over a month
11 14%

How the animals did

Recovered
7 4.1%
Still unwell when reported
48 28%
Died
37 22%
Euthanised
20 12%
Not known
58 34%

Problems reported at the same time

Age of the animals

Under 1 year
31
1–3 years
31
4–7 years
39
8–11 years
32
12+ years
35

About this medicine

Selamectin prevents heartworm and treats fleas, ear mites and some worms (spot-on).

Products with this ingredient include Revolution. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Some herding breeds (for example Collies) carry the MDR1 gene variant and can be more sensitive to this drug class at high doses.

Questions owners ask

Can Selamectin cause abnormal radiograph finding in cats?
170 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).

Abnormal radiograph finding with similar medicines

All reported side effects of Selamectin in cats · Medicines most reported with abnormal radiograph finding