Lameness after Ivermectin + Pyrantel (Heartgard Plus) in dogs

319 reports to the FDA describe lameness in dogs given Ivermectin + Pyrantel. That is 0.2% of all reports for this medicine, compared with 0.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

319Reports

43%Marked serious

22%Recovered

8.5%Died or euthanised

23 daysTypical onset

How soon it started

Same day

25 15%

1–2 days

27 16%

3–7 days

8 4.8%

1–4 weeks

31 19%

Over a month

76 46%

How the animals did

Recovered

57 18%

Recovered with lasting effects

13 4.1%

Still unwell when reported

51 16%

Died

12 3.8%

Euthanised

15 4.7%

Not known

171 54%

Problems reported at the same time

Lethargy

101 32%

Loss of appetite

72 23%

Vomiting

51 16%

Didn't prevent heartworm

41 13%

41 13%

28 8.8%

26 8.2%

23 7.2%

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 lameness in dogs?: 319 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 23 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).

Lameness with similar medicines

Lameness after Milbemycin Oxime + Spinosad (Trifexis) 452 reports · 0.3% of its reports
Lameness after Moxidectin (ProHeart 6) 363 reports · 0.7% of its reports
Lameness after Milbemycin Oxime + Praziquantel (Interceptor Plus) 233 reports · 0.7% of its reports
Lameness after Milbemycin Oxime (Interceptor) 115 reports · 0.4% of its reports
Lameness after Selamectin (Revolution) 100 reports · 0.3% of its reports
Lameness after Ivermectin (Heartgard) 59 reports · 0.5% of its reports

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