Stumbling gait after Ivermectin (Heartgard) in dogs

The FDA has received 65 reports of stumbling gait in dogs after Ivermectin. That is 0.5% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

65Reports

49%Marked serious

55%Recovered

6.2%Died or euthanised

30 daysTypical onset

How soon it started

Same day

8 19%

1–2 days

1 2.3%

3–7 days

2 4.7%

1–4 weeks

11 26%

Over a month

21 49%

How the animals did

Recovered

30 46%

Recovered with lasting effects

6 9.2%

Still unwell when reported

3 4.6%

Died

1 1.5%

Euthanised

3 4.6%

Not known

22 34%

Problems reported at the same time

Lethargy

17 26%

Eye or vision problems

15 23%

13 20%

12 18%

12 18%

11 17%

9 14%

8 12%

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).

Products with this ingredient include Heartgard. 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 cause stumbling gait in dogs?: 65 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 30 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 Ivermectin + Pyrantel (Heartgard Plus) 152 reports · 0.1% of its reports
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

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