Neutrophilia after Ivermectin (Heartgard) in dogs

The FDA has received 69 reports of neutrophilia in dogs after Ivermectin. That is 0.6% of all reports for this medicine, compared with 0.6% across reports for all dog medicines.

69Reports

78%Marked serious

13%Recovered

35%Died or euthanised

51 daysTypical onset

How soon it started

Same day

7 16%

1–2 days

2 4.7%

3–7 days

1 2.3%

1–4 weeks

8 19%

Over a month

25 58%

How the animals did

Recovered

6 8.7%

Recovered with lasting effects

3 4.3%

Still unwell when reported

26 38%

Died

6 8.7%

Euthanised

18 26%

Not known

10 14%

Problems reported at the same time

41 59%

34 49%

32 46%

30 43%

28 41%

24 35%

23 33%

23 33%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Ivermectin prevents heartworm disease (monthly).

Products with this ingredient include Heartgard. 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 Ivermectin cause neutrophilia in dogs?: 69 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 51 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).

Neutrophilia with similar medicines

Neutrophilia after Ivermectin + Pyrantel (Heartgard Plus) 327 reports · 0.2% of its reports
Neutrophilia after Milbemycin Oxime + Spinosad (Trifexis) 440 reports · 0.3% of its reports
Neutrophilia after Moxidectin (ProHeart 6) 429 reports · 0.8% of its reports
Neutrophilia after Milbemycin Oxime + Praziquantel (Interceptor Plus) 133 reports · 0.4% of its reports
Neutrophilia after Milbemycin Oxime (Interceptor) 56 reports · 0.2% of its reports
Neutrophilia after Selamectin (Revolution) 75 reports · 0.3% of its reports
Neutrophilia after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 20 reports · 0.2% of its reports

All reported side effects of Ivermectin in dogs · Medicines most reported with neutrophilia