Hind limb paresis after Ivermectin + Pyrantel (Heartgard Plus) in dogs

151 reports to the FDA describe hind limb paresis in dogs given Ivermectin + Pyrantel. That is 0.1% of all reports for this medicine, compared with 0.3% across reports for all dog medicines, so it is reported less often than average with this medicine.

151Reports

39%Marked serious

18%Recovered

12%Died or euthanised

3 daysTypical onset

How soon it started

Same day

22 39%

1–2 days

6 11%

3–7 days

5 8.9%

1–4 weeks

10 18%

Over a month

13 23%

How the animals did

Recovered

26 17%

Recovered with lasting effects

1 0.7%

Still unwell when reported

10 6.6%

Died

13 8.6%

Euthanised

5 3.3%

Not known

96 64%

Problems reported at the same time

38 25%

36 24%

28 19%

23 15%

23 15%

17 11%

16 11%

15 9.9%

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 hind limb paresis in dogs?: 151 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 3 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 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
Hind limb paresis after Ivermectin (Heartgard) 49 reports · 0.4% of its reports

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