Hind limb paresis after Ivermectin (Heartgard) in dogs

The FDA has received 49 reports of hind limb paresis in dogs after Ivermectin. That is 0.4% of all reports for this medicine, compared with 0.3% across reports for all dog medicines.

49Reports

29%Marked serious

14%Recovered

14%Died or euthanised

2 daysTypical onset

How soon it started

Same day

5 42%

1–2 days

2 17%

3–7 days

1 8.3%

1–4 weeks

2 17%

Over a month

2 17%

How the animals did

Recovered

5 10%

Recovered with lasting effects

2 4.1%

Still unwell when reported

4 8.2%

Died

6 12%

Euthanised

1 2.0%

Not known

31 63%

Problems reported at the same time

Wobbliness (ataxia)

16 33%

Tremors

14 29%

Lethargy

11 22%

Eye or vision problems

9 18%

8 16%

7 14%

7 14%

6 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 hind limb paresis in dogs?: 49 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).

Hind limb paresis with similar medicines

Hind limb paresis after Ivermectin + Pyrantel (Heartgard Plus) 151 reports · 0.1% of its reports
Hind limb paresis after Milbemycin Oxime + Spinosad (Trifexis) 91 reports · 0.1% of its reports
Hind limb paresis after Moxidectin (ProHeart 6) 173 reports · 0.3% of its reports
Hind limb paresis after Milbemycin Oxime + Praziquantel (Interceptor Plus) 26 reports · 0.1% of its reports
Hind limb paresis after Milbemycin Oxime (Interceptor) 50 reports · 0.2% of its reports
Hind limb paresis after Selamectin (Revolution) 65 reports · 0.2% of its reports

All reported side effects of Ivermectin in dogs · Medicines most reported with hind limb paresis