Collapse after Ivermectin + Pyrantel (Heartgard Plus) in dogs

432 reports to the FDA describe collapse in dogs given Ivermectin + Pyrantel. That is 0.3% of all reports for this medicine, compared with 0.9% across reports for all dog medicines, so it is reported less often than average with this medicine.

432Reports

66%Marked serious

24%Recovered

26%Died or euthanised

9 daysTypical onset

How soon it started

Same day

62 28%

1–2 days

31 14%

3–7 days

15 6.7%

1–4 weeks

46 21%

Over a month

70 31%

How the animals did

Recovered

95 22%

Recovered with lasting effects

9 2.1%

Still unwell when reported

47 11%

Died

80 19%

Euthanised

33 7.6%

Not known

168 39%

Problems reported at the same time

142 33%

111 26%

110 25%

93 22%

62 14%

62 14%

57 13%

55 13%

Age of the animals

Under 1 year

1–3 years

124

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 collapse in dogs?: 432 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 9 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).

Collapse with similar medicines

Collapse after Milbemycin Oxime + Spinosad (Trifexis) 471 reports · 0.4% of its reports
Collapse after Moxidectin (ProHeart 6) 1,511 reports · 3.0% of its reports
Collapse after Milbemycin Oxime + Praziquantel (Interceptor Plus) 153 reports · 0.5% of its reports
Collapse after Milbemycin Oxime (Interceptor) 163 reports · 0.5% of its reports
Collapse after Selamectin (Revolution) 115 reports · 0.4% of its reports
Collapse after Ivermectin (Heartgard) 109 reports · 0.9% of its reports
Collapse after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 60 reports · 0.7% of its reports

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