Decreased red blood cell count after Ilunocitinib (Zenrelia) in dogs

The FDA has received 113 reports of decreased red blood cell count in dogs after Ilunocitinib. That is 5.1% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported unusually often with this medicine.

113Reports
34%Marked serious
9.7%Recovered
15%Died or euthanised
76 daysTypical onset
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How soon it started

Same day
2 2.1%
1–2 days
0 0.0%
3–7 days
2 2.1%
1–4 weeks
19 20%
Over a month
73 76%

How the animals did

Recovered
11 9.7%
Still unwell when reported
38 34%
Died
2 1.8%
Euthanised
15 13%
Not known
47 42%

Problems reported at the same time

Age of the animals

Under 1 year
1
1–3 years
12
4–7 years
53
8–11 years
33
12+ years
11

About this medicine

Ilunocitinib controls itching from allergies (tablet, a JAK inhibitor).

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

Questions owners ask

Can Ilunocitinib cause decreased red blood cell count in dogs?
113 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 76 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).

Decreased red blood cell count with similar medicines

All reported side effects of Ilunocitinib in dogs · Medicines most reported with decreased red blood cell count