Heart murmur after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 109 reports of heart murmur in dogs after Ivermectin + Pyrantel. That is 0.1% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported less often than average with this medicine.

109Reports

73%Marked serious

17%Recovered

17%Died or euthanised

9 daysTypical onset

How soon it started

Same day

14 28%

1–2 days

7 14%

3–7 days

3 6.0%

1–4 weeks

8 16%

Over a month

18 36%

How the animals did

Recovered

9 8.3%

Recovered with lasting effects

10 9.2%

Still unwell when reported

24 22%

Died

10 9.2%

Euthanised

8 7.3%

Not known

48 44%

Problems reported at the same time

Didn't prevent heartworm

29 27%

27 25%

23 21%

22 20%

22 20%

21 19%

17 16%

16 15%

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). 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 heart murmur in dogs?: 109 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).

Heart murmur with similar medicines

Heart murmur after Milbemycin Oxime + Spinosad (Trifexis) 327 reports · 0.3% of its reports
Heart murmur after Moxidectin (ProHeart 6) 75 reports · 0.1% of its reports
Heart murmur after Milbemycin Oxime + Praziquantel (Interceptor Plus) 95 reports · 0.3% of its reports
Heart murmur after Milbemycin Oxime (Interceptor) 32 reports · 0.1% of its reports
Heart murmur after Ivermectin (Heartgard) 32 reports · 0.3% of its reports

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