Decreased activity after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 64 reports of decreased activity in dogs after Ivermectin + Pyrantel. That is 0.0% 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.

64Reports

45%Marked serious

36%Recovered

4.7%Died or euthanised

29 daysTypical onset

How soon it started

Same day

13 30%

1–2 days

3 7.0%

3–7 days

2 4.7%

1–4 weeks

4 9.3%

Over a month

21 49%

How the animals did

Recovered

21 33%

Recovered with lasting effects

2 3.1%

Still unwell when reported

12 19%

Died

3 4.7%

Not known

26 41%

Problems reported at the same time

24 38%

22 34%

20 31%

9 14%

Didn't work as expected

9 14%

Didn't prevent heartworm

7 11%

Kidney problems

7 11%

Diarrhea

7 11%

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 decreased activity in dogs?: 64 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 29 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 activity with similar medicines

Decreased activity after Milbemycin Oxime + Spinosad (Trifexis) 378 reports · 0.3% of its reports
Decreased activity after Moxidectin (ProHeart 6) 37 reports · 0.1% of its reports
Decreased activity after Milbemycin Oxime + Praziquantel (Interceptor Plus) 60 reports · 0.2% of its reports
Decreased activity after Milbemycin Oxime (Interceptor) 26 reports · 0.1% of its reports
Decreased activity after Ivermectin (Heartgard) 27 reports · 0.2% of its reports

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