Stumbling gait after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 152 reports of stumbling gait 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.

152Reports

48%Marked serious

36%Recovered

7.9%Died or euthanised

2 daysTypical onset

How soon it started

Same day

29 35%

1–2 days

16 19%

3–7 days

6 7.1%

1–4 weeks

11 13%

Over a month

22 26%

How the animals did

Recovered

50 33%

Recovered with lasting effects

5 3.3%

Still unwell when reported

20 13%

Died

7 4.6%

Euthanised

5 3.3%

Not known

65 43%

Problems reported at the same time

49 32%

35 23%

31 20%

28 18%

23 15%

22 14%

22 14%

20 13%

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 stumbling gait in dogs?: 152 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 2 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).

Stumbling gait with similar medicines

Stumbling gait after Milbemycin Oxime + Spinosad (Trifexis) 236 reports · 0.2% of its reports
Stumbling gait after Moxidectin (ProHeart 6) 78 reports · 0.2% of its reports
Stumbling gait after Milbemycin Oxime + Praziquantel (Interceptor Plus) 63 reports · 0.2% of its reports
Stumbling gait after Milbemycin Oxime (Interceptor) 34 reports · 0.1% of its reports
Stumbling gait after Selamectin (Revolution) 32 reports · 0.1% of its reports
Stumbling gait after Ivermectin (Heartgard) 65 reports · 0.5% of its reports

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