Neutrophilia after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 327 reports of neutrophilia in dogs after Ivermectin + Pyrantel. That is 0.2% of all reports for this medicine, compared with 0.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

327Reports

70%Marked serious

17%Recovered

19%Died or euthanised

8 daysTypical onset

How soon it started

Same day

43 21%

1–2 days

37 18%

3–7 days

23 11%

1–4 weeks

45 22%

Over a month

60 29%

How the animals did

Recovered

47 14%

Recovered with lasting effects

9 2.8%

Still unwell when reported

77 24%

Died

27 8.3%

Euthanised

36 11%

Not known

131 40%

Problems reported at the same time

198 61%

160 49%

157 48%

152 46%

152 46%

105 32%

82 25%

77 24%

Age of the animals

Under 1 year

1–3 years

101

4–7 years

8–11 years

12+ years

About this medicine

Ivermectin prevents heartworm disease (monthly). Pyrantel treats roundworms and hookworms.

Products with this combination include Heartgard Plus, Tri-Heart Plus, Iverhart Plus. 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 + Pyrantel cause neutrophilia in dogs?: 327 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 8 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 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 (Heartgard) 69 reports · 0.6% of its reports
Neutrophilia after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 20 reports · 0.2% of its reports

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